CVE-2026-33808— @fastify/express vulnerable to middleware authentication bypass via URL normalization gaps (duplicate slashes and semicolons)

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

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.

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解释冲突

@fastify/express 安全漏洞

@fastify/express是Fastify开源的一个兼容性插件。 @fastify/express 4.0.4及之前版本存在安全漏洞，该漏洞源于在启用Fastify路由器规范化选项时，未在将URL传递给Express中间件之前对其进行规范化，可能导致通过重复斜杠或分号分隔符绕过路径范围的身份验证中间件。

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