chore(deps): update dependency axios to v1.15.2 [security]#540
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This PR contains the following updates:
1.15.0→1.15.2Axios: Null Byte Injection via Reverse-Encoding in AxiosURLSearchParams
CVE-2026-42040 / GHSA-xhjh-pmcv-23jw
More information
Details
Vulnerability Disclosure: Null Byte Injection via Reverse-Encoding in AxiosURLSearchParams
Summary
The
encode()function inlib/helpers/AxiosURLSearchParams.jscontains a character mapping (charMap) at line 21 that reverses the safe percent-encoding of null bytes. AfterencodeURIComponent('\x00')correctly produces the safe sequence%00, the charMap entry'%00': '\x00'converts it back to a raw null byte.This is a clear encoding defect: every other charMap entry encodes in the safe direction (literal → percent-encoded), while this single entry decodes in the opposite (dangerous) direction.
Severity: Low (CVSS 3.7)
Affected Versions: All versions containing this charMap entry
Vulnerable Component:
lib/helpers/AxiosURLSearchParams.js:21CWE
CVSS 3.1
Score: 3.7 (Low)
Vector:
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:NbuildURL) uses its ownencodefunction which does NOT have this bug. Only triggered via directAxiosURLSearchParams.toString()without an encoder, or via customparamsSerializerdelegationVulnerable Code
File:
lib/helpers/AxiosURLSearchParams.js, lines 13-26Why the Standard Flow Is NOT Affected
Proof of Concept
Verified PoC Output
Impact Analysis
Primary impact is limited because the standard axios request flow is not affected. However:
AxiosURLSearchParamsdirectly for custom serialization are affectedparamsSerializer.encodethat delegates to the internal encoder triggers the bugIf null bytes reach a downstream C-based parser, impacts include URL truncation, WAF bypass, and log injection.
Recommended Fix
Remove the
%00entry from charMap and update the regex:Resources
Timeline
Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Axios has prototype pollution read-side gadgets in HTTP adapter that allow credential injection and request hijacking
CVE-2026-42264 / GHSA-q8qp-cvcw-x6jj
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Details
Summary
Five config properties in the HTTP adapter are read via direct property access without
hasOwnPropertyguards, making them exploitable as prototype pollution gadgets. WhenObject.prototypeis polluted by another dependency in the same process, axios silently picks up these polluted values on every outbound HTTP request.Affected Properties
config.auth(lib/adapters/http.jsline 617) Injects attacker-controlledAuthorizationheader on all requests.config.baseURL(lib/helpers/resolveConfig.jsline 18) Redirects all requests using relative URLs to an attacker-controlled server.config.socketPath(lib/adapters/http.jsline 669) Redirects requests to internal Unix sockets (e.g. Docker daemon).config.beforeRedirect(lib/adapters/http.jsline 698) Executes attacker-supplied callback during HTTP redirects.config.insecureHTTPParser(lib/adapters/http.jsline 712) Enables Node.js insecure HTTP parser on all requests.Proof of Concept
Impact
Authorizationheader, leaking request contents to any server that logs auth headers.Root Cause
mergeConfig()iteratesObject.keys({...config1, ...config2}), which only returns own properties. When neither the defaults nor the user config sets these properties, they are absent from the merged config. The HTTP adapter then reads them via direct property access (config.auth,config.socketPath, etc.), which traverses the prototype chain and picks up polluted values.The
own()helper atlib/adapters/http.jsline 336 exists and guards 8 other properties (data,lookup,family,httpVersion,http2Options,responseType,responseEncoding,transport) from this exact attack. The 5 properties listed above are not included in this protection.Suggested Fix
Apply the existing
own()helper to all affected properties:Same pattern for
socketPath,beforeRedirect,insecureHTTPParser, and ahasOwnPropertycheck forbaseURLinresolveConfig.js.Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Axios: Invisible JSON Response Tampering via Prototype Pollution Gadget in
parseReviverCVE-2026-42044 / GHSA-3w6x-2g7m-8v23
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Details
Vulnerability Disclosure: Invisible JSON Response Tampering via Prototype Pollution Gadget in
parseReviverSummary
The Axios library is vulnerable to a Prototype Pollution "Gadget" attack that allows any
Object.prototypepollution in the application's dependency tree to be escalated into surgical, invisible modification of all JSON API responses — including privilege escalation, balance manipulation, and authorization bypass.The default
transformResponsefunction atlib/defaults/index.js:124callsJSON.parse(data, this.parseReviver), wherethisis the merged config object. BecauseparseReviveris not present in Axios defaults, not validated byassertOptions, and not subject to any constraints, a pollutedObject.prototype.parseReviverfunction is called for every key-value pair in every JSON response, allowing the attacker to selectively modify individual values while leaving the rest of the response intact.This is strictly more powerful than the
transformResponsegadget because:Severity: Critical (CVSS 9.1)
Affected Versions: All versions (v0.x - v1.x including v1.15.0)
Vulnerable Component:
lib/defaults/index.js:124(JSON.parse with prototype-inherited reviver)CWE
CVSS 3.1
Score: 9.1 (Critical)
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NapiKey: "sk-secret-internal-key"is capturedisAdmin: false → true,role: "viewer" → "admin",balance: 100 → 999999. The response looks completely normal except for the surgically altered valuesComparison with All Known Axios PP Gadgets
Object.prototype['header']Object.prototype.transformResponseObject.prototype.proxyObject.prototype.parseRevivertruetruetrue(obvious)this.auth+ raw responseassertOptionsvalidatesUsage of "Helper" Vulnerabilities
This vulnerability requires Zero Direct User Input.
If an attacker can pollute
Object.prototypevia any other library in the stack (e.g.,qs,minimist,lodash,body-parser), the pollutedparseReviverfunction is automatically used by every Axios request that receives a JSON response. The developer's code is completely safe — no configuration errors needed.Root Cause Analysis
The Attack Path
Why
parseReviverBypasses ALL Existing ProtectionsNot in defaults (
lib/defaults/index.js):parseReviveris not defined in the defaults object, somergeConfig'sObject.keys({...defaults, ...userConfig})iteration never encounters it. The merged config has no ownparseReviverproperty.Not in assertOptions schema (
lib/core/Axios.js:135-142): The schema only contains{baseUrl, withXsrfToken}.parseReviveris not validated.No type check: The
JSON.parseAPI accepts any function as a reviver. There is no check thatthis.parseReviveris intentionally set.Works INSIDE the default transform: Unlike
transformResponsepollution (which replaces the entire transform and is caught byassertOptions),parseReviverpollution injects into the DEFAULTtransformResponsefunction'sJSON.parsecall. The default function itself is not replaced, soassertOptionshas nothing to catch.Vulnerable Code
File:
lib/defaults/index.js, line 124Proof of Concept
Verified PoC Output
Impact Analysis
1. Authorization / Privilege Escalation
2. Financial Manipulation
3. Security Control Bypass
4. Silent Data Exfiltration
The reviver function receives the original value before modification. The attacker can silently capture all API keys, tokens, internal data, and PII from every JSON response while the application continues to function normally.
5. Universal and Invisible
Recommended Fix
Fix 1: Use
hasOwnPropertycheck before usingparseReviverFix 2: Use null-prototype config object
Fix 3: Validate
parseRevivertype and sourceRelationship to Other Reported Gadgets
This vulnerability shares the same root cause class — unsafe prototype chain traversal on the merged config object — with two other reported gadgets:
transformResponsemergeConfig.js:49(defaultToConfig2)mergeConfig.jstrueproxyhttp.js:670(direct property access)http.jsparseReviverdefaults/index.js:124(this.parseReviver)defaults/index.jsWhy These Are Distinct Vulnerabilities
Object.prototypekey.transformResponseenters viamergeConfig;proxyis read directly byhttp.js;parseReviveris read inside the defaulttransformResponsefunction'sJSON.parsecall.mergeConfig.js(axios_26) does NOT fixdefaults/index.js:124(this vulnerability). Fixinghttp.js:670(axios_30) does NOT fix this either. Each requires a separate patch.transformResponseis constrained to returntrue;proxyrequires a proxy server;parseReviverenables constraint-free selective value modification.Comprehensive Fix
While each vulnerability requires a location-specific patch, the comprehensive fix is to use null-prototype objects (
Object.create(null)) for the merged config inmergeConfig.js, which would eliminate prototype chain traversal for all config property accesses and address all three gadgets at once. The maintainer may choose to assign a single CVE covering the root cause or separate CVEs for each distinct exploitation path — we defer to the maintainer's judgment on this.Resources
Timeline
Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Axios: Incomplete Fix for CVE-2025-62718 — NO_PROXY Protection Bypassed via RFC 1122 Loopback Subnet (127.0.0.0/8) in Axios 1.15.0
CVE-2026-42043 / GHSA-pmwg-cvhr-8vh7
More information
Details
1. Executive Summary
This report documents an incomplete security patch for the previously disclosed vulnerability GHSA-3p68-rc4w-qgx5 (CVE-2025-62718), which affects the
NO_PROXYhostname resolution logic in the Axios HTTP library.Background — The Original Vulnerability
The original vulnerability (GHSA-3p68-rc4w-qgx5) disclosed that Axios did not normalize hostnames before comparing them against
NO_PROXYrules. Specifically, a request tohttp://localhost./(with a trailing dot) orhttp://[::1]/(with IPv6 bracket notation) would bypass NO_PROXY matching entirely and be forwarded to the configured HTTP proxy — even whenNO_PROXY=localhost,127.0.0.1,::1was explicitly set by the developer to protect loopback services.The Axios maintainers addressed this in version 1.15.0 by introducing a
normalizeNoProxyHost()function inlib/helpers/shouldBypassProxy.js, which strips trailing dots from hostnames and removes brackets from IPv6 literals before performing the NO_PROXY comparison.The Incomplete Patch — This Finding
While the patch correctly addresses the specific cases reported (trailing dot normalization and IPv6 bracket removal), the fix is architecturally incomplete.
The patch introduced a hardcoded set of recognized loopback addresses:
However, RFC 1122 §3.2.1.3 explicitly defines the entire 127.0.0.0/8 subnet as the IPv4 loopback address block not just the single address
127.0.0.1. On all major operating systems (Linux, macOS, Windows with WSL), any IP address in the range127.0.0.2through127.255.255.254is a valid, functional loopback address that routes to the local machine.As a result, an attacker who can influence the target URL of an Axios request can substitute 127.0.0.1 with any other address in the
127.0.0.0/8range (e.g.,127.0.0.2,127.0.0.100,127.1.2.3) to completely bypass theNO_PROXYprotection even in the fully patched Axios 1.15.0 release.Verification
This bypass has been independently verified on:
The Proof-of-Concept demonstrates that while
localhost,localhost., and[::1]are correctly blocked by the patched version, requests to127.0.0.2,127.0.0.100, and127.1.2.3are transparently forwarded to the attacker-controlled proxy server, confirming that the patch does not cover the full RFC-defined loopback address space.2. Deep-Dive: Technical Root Cause Analysis
2.1 Vulnerable File & Location
2.2 How Axios Routes HTTP Requests The Call Chain
When Axios dispatches any HTTP request,
lib/adapters/http.jscallssetProxy(), which invokesshouldBypassProxy()to decide whether to honour a configured proxy:shouldBypassProxy()is the single gatekeeper for NO_PROXY enforcement. A bypass here means all proxy protection fails silently.2.3 The Original Vulnerability (GHSA-3p68-rc4w-qgx5)
Before Axios 1.15.0, hostnames were compared against
NO_PROXYusing a raw literal string match with no normalization:Both
localhost.(FQDN trailing dot, RFC 1034 §3.1) and[::1](bracketed IPv6 literal, RFC 3986 §3.2.2) are canonical representations of loopback addresses, but Axios treated them as unknown hosts.2.4 What the Patch Fixed (Axios 1.15.0)
The patch introduced three changes inside
lib/helpers/shouldBypassProxy.js:Fix A
normalizeNoProxyHost()(Lines 47–57)Strips alternate representations before comparison:
Fix B Cross-Loopback Equivalence (Lines 1–3 & 108)
Allows
127.0.0.1andlocalhostto match each other interchangeably:Fix C Normalization Applied on Both Sides (Lines 81 & 90)
2.5 The Incomplete Patch Exact Root Cause
The fundamental flaw resides in Line 1:
*RFC 1122 §3.2.1.3 is unambiguous:
This means all addresses from
127.0.0.1through127.255.255.254are valid loopback addresses on any RFC-compliant operating system. On Linux, the entire/8block is routed to thelointerface by default. The patch recognises only127.0.0.1, leaving16,777,213valid loopback addresses unprotected.2.6 Step-by-Step Bypass Execution Trace
Environment:
Annotated execution of shouldBypassProxy("http://127.0.0.2:9191/internal-api"):
2.7 Why the Patch Design Is Flawed
The patch addresses the symptom (two specific alternate representations) rather than the root cause (an incomplete definition of what constitutes a loopback address).
Real-world services that commonly bind to non-standard loopback addresses include:
3. Comprehensive Attack Vector & Proof of Concept
3.1 Reproduction Steps
Step 1 — Create a fresh project directory
Step 2 — Initialize the project with the patched Axios version
Create
package.json:Install dependencies:
Verify the installed version:
Step 3 — Create the PoC file (
poc.js)Step 4 — Execute the PoC
3.2 Observed Output
The following output was captured during testing on Kali Linux with Axios 1.15.0:
3.3 Analysis of Results
The output conclusively demonstrates the following:
Patched cases behave correctly: Requests to
localhost,localhost.(trailing dot), and[::1](bracketed IPv6) all result in a direct connection, confirming that the existing patch in Axios 1.15.0 correctly handles the cases reported in GHSA-3p68-rc4w-qgx5.Bypass cases confirm the incomplete patch: Requests to
127.0.0.2,127.0.0.100, and127.1.2.3all of which are valid loopback addresses within the127.0.0.0/8subnet as defined byRFC 1122 §3.2.1.3are transparently forwarded to the attacker-controlled proxy server. The proxy receives the full request including the HTTP method, target URL, andHostheader, demonstrating that any response from an internal service bound to these addresses would be fully intercepted.This confirms that the
NO_PROXYprotection configured by the developer (localhost,127.0.0.1,::1) fails silently for the entire127.0.0.0/8address range beyond127.0.0.1, providing a reproducible and reliable bypass of the security control introduced by the patch.4. Impact Assessment
This vulnerability is a security control bypass specifically an incomplete patch that allows an attacker to circumvent the
NO_PROXYprotection mechanism in Axios by using any loopback addresses within the127.0.0.0/8subnet other than127.0.0.1. The result is that traffic intended to remain private and direct is silently intercepted by a configured proxy server.4.1 Who Is Impacted?
Primary Target — Node.js Backend Applications
Any Node.js application that meets all three of the following conditions is vulnerable:
Affected Deployment Environments
Scale of Exposure
Axios is one of the most widely used HTTP client libraries in the JavaScript ecosystem, with over 500 million weekly downloads on npm. Any application in the above categories using Axios 1.15.0 is affected, regardless of whether the developer is aware of the underlying proxy routing logic.
4.3 Impact Details
Impact 1 Silent Interception of Internal Service Traffic
When an application makes a request to an internal loopback service using a non-standard loopback address (e.g.,
http://127.0.0.2/admin), Axios silently routes the request through the configured proxy instead of connecting directly.The developer receives no error or warning. From the application's perspective, the request succeeds normally.
Impact 2 — SSRF Mitigation Bypass
Many applications implement SSRF protections by configuring
NO_PROXYto prevent requests to loopback addresses from being forwarded externally. This bypass defeats that protection entirely for any loopback address beyond127.0.0.1.An attacker who can influence the target URL of an Axios request through user-supplied input, redirect chains, or other SSRF vectors can exploit this gap to reach internal services that the developer explicitly intended to protect.
Impact 3 — Cloud Metadata Service Exposure
In cloud environments (AWS, GCP, Azure), SSRF vulnerabilities are particularly severe because they can be used to access the instance metadata service and retrieve IAM credentials, enabling full cloud account compromise.
While the AWS IMDSv2 service is reachable at
169.254.169.254(not a loopback address), many cloud deployments run internal metadata proxies, credential servers, or service discovery endpoints bound to non-standard loopback addresses within the127.0.0.0/8range. An attacker reaching any of these services through the bypass could:Impact 4 — Confidential Data Exfiltration
Any internal service binding to a
127.x.x.xaddress other than127.0.0.1is fully exposed. This includes:Impact 5 — No Indication of Compromise
A particularly dangerous characteristic of this vulnerability is that it is completely silent neither the application nor the developer receives any indication that requests are being routed incorrectly. There are no error messages, no exceptions thrown, and no changes in application behaviour. The proxy interception is entirely transparent from the application's perspective, making detection extremely difficult without active network monitoring.
4.4 Comparison with Original Vulnerability
The severity of this finding is equivalent to the original vulnerability because the attack conditions, exploitation technique, and resulting impact are identical. The only difference is the specific input used to trigger the bypass, which the existing patch completely fails to address.
5. Technical Remediation & Proposed Fix
5.1 Vulnerable Code Block
The vulnerability resides in
lib/helpers/shouldBypassProxy.jsat lines 1–3. The following is the exact code extracted from Axios 1.15.0:This hardcoded
Setis subsequently used at line 108 during the final NO_PROXY match evaluation:Why this is dangerous: The
Setperforms a strict membership check. Any IPv4 loopback address outside the three hardcoded entries returnsfalse, causingshouldBypassProxy()to returnfalseand silently route the request through the configured proxy.5.2 Proposed Patched Code
Replace lines 1–3 in
lib/helpers/shouldBypassProxy.jswith the following RFC-compliant implementation:5.3 Diff View — Before vs After
All other code in
shouldBypassProxy.jsremains unchanged. No other files require modification.5.4 Why This Fix Must Be Applied
Reason 1 — RFC 1122 Compliance
The current implementation violates RFC 1122 §3.2.1.3, which defines the entire
127.0.0.0/8block as the IPv4 loopback address range not just the single address127.0.0.1. The proposed fix aligns Axios with the standard, ensuring that all valid loopback addresses are recognised and handled consistently.Reason 2 — The Existing Patch Has Already Failed Once
The patch for GHSA-3p68-rc4w-qgx5 was released with the explicit intent of securing NO_PROXY hostname matching for loopback addresses. Within the same release (1.15.0), the protection can be bypassed by substituting
127.0.0.1with any other address in the127.0.0.0/8range. Leaving this gap unaddressed means that the patch creates a false sense of security developers believe their loopback traffic is protected when it is not.Reason 3 — Real Operating System Behaviour
On Linux the dominant platform for Node.js server deployments the kernel routes the entire
127.0.0.0/8subnet to the loopback interfaceloby default. This means any address in that range functions identically to127.0.0.1at the networking level.Axios's current implementation does not reflect this operating system behaviour, resulting in an inconsistency between what the OS considers loopback and what Axios treats as loopback.
Reason 4 — The Proposed Fix Has Zero Performance Impact
The existing solution uses a
Set.has()lookup an O(1) operation. The proposed fix replaces this with:'localhost','::1') — O(1)split('.')and array validation — O(1) with a fixed-length array of 4 elementsThe computational cost is equivalent or lower than the current approach, and the fix introduces no new external dependencies.
Reason 5 — The Fix Is Minimal and Surgical
The proposed change modifies only 3 lines of a single file. It does not alter:
parseNoProxyEntry()functionnormalizeNoProxyHost()functionshouldBypassProxy()main function logicThis minimises regression risk and makes the fix straightforward to review, test, and backport to older supported branches.
Reason 6 — Resilient to Alternative IP Encodings
Because Axios normalises the request URL using Node's native
new URL()parser before passing it toshouldBypassProxy(), alternative IP encodings (such as octal0177.0.0.1, hex0x7f.0.0.1, or integer2130706433) are already resolved into their standard IPv4 dotted-decimal format. This means the proposed.split('.')validation logic is completely robust and cannot be bypassed using URL-encoded IP obfuscation techniques.5.5 Additional Recommendation — IPv6 Loopback Range
While the primary bypass demonstrated in this report targets the IPv4
127.0.0.0/8range, the Axios team should also consider validating the full IPv6 loopback representation. The current implementation recognises only::1. A more complete check would also handle the full-form notation:Normalising these representations before comparison would make the NO_PROXY implementation comprehensively RFC-compliant across both IPv4 and IPv6 address families.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Axios: Authentication Bypass via Prototype Pollution Gadget in
validateStatusMerge StrategyCVE-2026-42041 / GHSA-w9j2-pvgh-6h63
More information
Details
Vulnerability Disclosure: Authentication Bypass via Prototype Pollution Gadget in
validateStatusMerge StrategySummary
The Axios library is