CVE-2026-76169

Description

fastify versions >= 4.0.0 and before 5.12.2 can route a malformed URL sent under one plugin prefix to the custom not-found handler of a different sibling plugin, and invoke it without the preHandler hook declared for that handler. The internal not-found router for encapsulated handlers dispatches malformed paths through a single shared handler pointer before URL decoding, ignoring the prefix and skipping the selected handler's normal lifecycle. An unauthenticated attacker can therefore reach an authentication-protected private fallback through an unrelated public prefix and read its full response, bypassing the authentication hook and breaking prefix encapsulation. Users should upgrade to fastify 5.12.2 or later.

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Produits concernés

• fastify
• Fastify fastify

Scores CVSS

Faiblesses (CWE)

• CWE-288

Références

• https://cna.openjsf.org/security-advisories.html Third Party Advisory
• https://github.com/fastify/fastify/security/advisories/GHSA-p68q-wchp-6fh7 MitigationVendor Advisory

Ailleurs

• NVD
• CVE.org
• CIRCL Vulnerability-Lookup
• CERT-FR
• GitHub Advisories