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fix(deps): update dependency undici to v6 [security]#892

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fix(deps): update dependency undici to v6 [security]#892
renovate[bot] wants to merge 1 commit intochore/renovateBaseBranchfrom
renovate/npm-undici-vulnerability

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@renovate renovate bot commented Jan 22, 2025 •
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This PR body was truncated due to platform limits.

This PR contains the following updates:

Package Change Age Confidence
undici (source) 5.28.4 → 6.24.0 age confidence

GitHub Vulnerability Alerts

CVE-2025-22150

Impact

Undici fetch() uses Math.random() to choose the boundary for a multipart/form-data request. It is known that the output of Math.random() can be predicted if several of its generated values are known.

If there is a mechanism in an app that sends multipart requests to an attacker-controlled website, they can use this to leak the necessary values. Therefore, An attacker can tamper with the requests going to the backend APIs if certain conditions are met.

Patches

This is fixed in 5.28.5; 6.21.1; 7.2.3.

Workarounds

Do not issue multipart requests to attacker controlled servers.

References

CVE-2025-47279

Impact

Applications that use undici to implement a webhook-like system are vulnerable. If the attacker set up a server with an invalid certificate, and they can force the application to call the webhook repeatedly, then they can cause a memory leak.

Patches

This has been patched in https://github.com/nodejs/undici/pull/4088.

Workarounds

If a webhook fails, avoid keep calling it repeatedly.

References

Reported as: https://github.com/nodejs/undici/issues/3895

CVE-2026-22036

Impact

The fetch() API supports chained HTTP encoding algorithms for response content according to RFC 9110 (e.g., Content-Encoding: gzip, br). This is also supported by the undici decompress interceptor.

However, the number of links in the decompression chain is unbounded and the default maxHeaderSize allows a malicious server to insert thousands compression steps leading to high CPU usage and excessive memory allocation.

Patches

Upgrade to 7.18.2 or 6.23.0.

Workarounds

It is possible to apply an undici interceptor and filter long Content-Encoding sequences manually.

References

CVE-2026-1525

Impact

Undici allows duplicate HTTP Content-Length headers when they are provided in an array with case-variant names (e.g., Content-Length and content-length). This produces malformed HTTP/1.1 requests with multiple conflicting Content-Length values on the wire.

Who is impacted:

  • Applications using undici.request(), undici.Client, or similar low-level APIs with headers passed as flat arrays
  • Applications that accept user-controlled header names without case-normalization

Potential consequences:

  • Denial of Service: Strict HTTP parsers (proxies, servers) will reject requests with duplicate Content-Length headers (400 Bad Request)
  • HTTP Request Smuggling: In deployments where an intermediary and backend interpret duplicate headers inconsistently (e.g., one uses the first value, the other uses the last), this can enable request smuggling attacks leading to ACL bypass, cache poisoning, or credential hijacking

Patches

Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later.

Workarounds

If upgrading is not immediately possible:

  1. Validate header names: Ensure no duplicate Content-Length headers (case-insensitive) are present before passing headers to undici
  2. Use object format: Pass headers as a plain object ({ 'content-length': '123' }) rather than an array, which naturally deduplicates by key
  3. Sanitize user input: If headers originate from user input, normalize header names to lowercase and reject duplicates

CVE-2026-1527

Impact

When an application passes user-controlled input to the upgrade option of client.request(), an attacker can inject CRLF sequences (\r\n) to:

  1. Inject arbitrary HTTP headers
  2. Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch)

The vulnerability exists because undici writes the upgrade value directly to the socket without validating for invalid header characters:

// lib/dispatcher/client-h1.js:1121
if (upgrade) {
  header += `connection: upgrade\r\nupgrade: ${upgrade}\r\n`
}

Patches

Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later.

Workarounds

Sanitize the upgrade option string before passing to undici:

function sanitizeUpgrade(value) {
  if (/[\r\n]/.test(value)) {
    throw new Error('Invalid upgrade value')
  }
  return value
}

client.request({
  upgrade: sanitizeUpgrade(userInput)
})

CVE-2026-2229

Impact

The undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range server_max_window_bits value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeError exception that is not caught, resulting in immediate process termination.

The vulnerability exists because:

  1. The isValidClientWindowBits() function only validates that the value contains ASCII digits, not that it falls within the valid range 8-15
  2. The createInflateRaw() call is not wrapped in a try-catch block
  3. The resulting exception propagates up through the call stack and crashes the Node.js process

Patches

Has the problem been patched? What versions should users upgrade to?

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

CVE-2026-1526

Description

The undici WebSocket client is vulnerable to a denial-of-service attack via unbounded memory consumption during permessage-deflate decompression. When a WebSocket connection negotiates the permessage-deflate extension, the client decompresses incoming compressed frames without enforcing any limit on the decompressed data size. A malicious WebSocket server can send a small compressed frame (a "decompression bomb") that expands to an extremely large size in memory, causing the Node.js process to exhaust available memory and crash or become unresponsive.

The vulnerability exists in the PerMessageDeflate.decompress() method, which accumulates all decompressed chunks in memory and concatenates them into a single Buffer without checking whether the total size exceeds a safe threshold.

Impact

  • Remote denial of service against any Node.js application using undici's WebSocket client
  • A single compressed WebSocket frame of ~6 MB can decompress to ~1 GB or more
  • Memory exhaustion occurs in native/external memory, bypassing V8 heap limits
  • No application-level mitigation is possible as decompression occurs before message delivery

Patches

Users should upgrade to fixed versions.

Workarounds

No workaround are possible.

Release Notes

nodejs/undici (undici)

v6.24.0

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What's Changed

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renovate bot commented Jan 22, 2025

Branch automerge failure

This PR was configured for branch automerge. However, this is not possible, so it has been raised as a PR instead.

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@renovate renovate bot force-pushed the renovate/npm-undici-vulnerability branch from 71c67dc to 92718af Compare May 15, 2025 15:13
@renovate renovate bot changed the title fix(deps): update dependency undici to v5.28.5 [security] fix(deps): update dependency undici to v5.29.0 [security] May 15, 2025
@renovate renovate bot force-pushed the renovate/npm-undici-vulnerability branch from 92718af to 9638ac5 Compare November 9, 2025 11:02
@renovate renovate bot force-pushed the renovate/npm-undici-vulnerability branch from 9638ac5 to d4c9897 Compare January 14, 2026 23:02
@renovate renovate bot changed the title fix(deps): update dependency undici to v5.29.0 [security] fix(deps): update dependency undici to v6 [security] Jan 14, 2026
@renovate renovate bot force-pushed the renovate/npm-undici-vulnerability branch from d4c9897 to 460d59f Compare March 13, 2026 23:09
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