CVE-2026-86206, CVE-2026-86207 N-able N-central Authenticati...

[carlospolop]

🤖 Automated Content Update

This PR was automatically generated by the HackTricks News Bot based on a technical blog post.

📝 Source Information

• Blog URL: https://rapid7.com/blog/post/ve-cve-2026-86206-cve-2026-86207-n-able-n-central-authentication-bypass-fixed
• Blog Title: CVE-2026-86206, CVE-2026-86207: N-able N-central Authentication Bypass (FIXED)
• Suggested Section: Pentesting Web -> Proxy / WAF Protections Bypass, with cross-references to Login Bypass and Web API Pentesting; a suitable new page would be 'Reverse-Proxy/Backend Path Canonicalization and Header Parser Differential Bypasses'.

🎯 Content Summary

Overview and impact. Rapid7 Labs researcher Stephen Fewer discovered two vulnerabilities in N-able N-central while investigating the earlier N-central authentication bypass CVE-2026-18577. When chained, CVE-2026-86206 and CVE-2026-86207 allow a remote unauthenticated attacker to bypass N-central's access controls, obtain a privileged SOAP session, and create a new attacker-controlled System administrator ...

🔧 Technical Details

Reverse-proxy/backend path canonicalization bypass: When a reverse proxy applies prefix-based access controls to the raw URI while a backend server canonicalizes semicolon path parameters before servlet dispatch, insert a semicolon into a protected path segment. For example, /dms;/services/ServerUI does not match a proxy block for /dms/services, but Jetty normalizes it to /dms/services/ServerUI and dispatches it to the protected SOAP servlet. The same pattern can target alternate mappings such as /internal;/dms/services2/ServerUI2. The defensive lesson is that every proxy, parser, router, and authorization filter must canonicalize and authorize the same path representation.

Forwarded-header parser differential and fail-open validation: A crafted quoted-pair such as Forwarded: for="127.0.0.\1" can produce different values in different HTTP components. One parser may ...

🤖 Agent Actions

Updated src/pentesting-web/proxy-waf-protections-bypass.md with:

• Semicolon path-parameter canonicalization bypasses.
• Forwarded quoted-pair parser differentials and fail-open validation.
• A four-case differential testing matrix and defensive logging guidance.
• Exception-driven pre-login session identity retention.
• Cross-references to SOAP/API pentesting and login bypass guidance.
• Numbered Rapid7 reference and inline citations.

Validation:

• git diff --check passed.
• Internal cross-reference paths verified.
• mdbook build could not run because mdbook is not installed.

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[carlospolop]

🔗 Additional Context

Original Blog Post: https://rapid7.com/blog/post/ve-cve-2026-86206-cve-2026-86207-n-able-n-central-authentication-bypass-fixed

Content Categories: Based on the analysis, this content was categorized under "Pentesting Web -> Proxy / WAF Protections Bypass, with cross-references to Login Bypass and Web API Pentesting; a suitable new page would be 'Reverse-Proxy/Backend Path Canonicalization and Header Parser Differential Bypasses'.".

Repository Maintenance:

• MD Files Formatting: 1032 files processed

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Bot Version: HackTricks News Bot v1.0