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CVE-2026-33808criticalCWE-436

@fastify/express vulnerable to middleware authentication bypass via URL normalization gaps (duplicate slashes and semicolons)

28Vexday Risk Score

Sin señal de explotación. Ningún artefacto público de explotación conocido hasta ahora.

ssvc Trackcvss 9.1epss 0.5%
probabilidad de explotación
0.5%top 61% de las CVE
explotación observada
noninguna fuente lo reporta
Impact@fastify/express v4.0.4 and earlier fails to normalize URLs before passing them to Express middleware when Fastify router normalization options are enabled. This allows complete bypass of path-scoped authentication middleware via duplicate slashes when ignoreDuplicateSlashes is enabled, or via semicolon delimiters when useSemicolonDelimiter is enabled. In both cases, Fastify router normalizes the URL and matches the route, but @fastify/express passes the original un-normalized URL to Express middleware, which fails to match and is skipped. An unauthenticated attacker can access protected routes by manipulating the URL path. PatchesUpgrade to @fastify/express v4.0.5 or later.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Productos afectados
fastify · @fastify/express