@fastify/static before version 10.1.3 contains an incomplete fix for a previous route guard bypass. The static file handler rejected only parent directory segments, but it did not canonicalize dot segments, duplicate slashes, encoded dots, or backslashes before route matching and before delegating to the send layer. As a result, an unauthenticated attacker could request a file protected by a route based guard using a non canonical path form that misses the guarded route yet resolves back onto the protected file, disclosing its contents. Applications that protect a subtree of the static root with a route based guard are affected, while applications relying on the allowedPath option are not. This is fixed in @fastify/static 10.1.3, which canonicalizes the pathname, including rejecting backslashes, on the path used for routing and serving.
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Thu, 06 Aug 2026 16:30:00 +0000
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ssvc
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Thu, 06 Aug 2026 15:30:00 +0000
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| Description | @fastify/static before version 10.1.3 contains an incomplete fix for a previous route guard bypass. The static file handler rejected only parent directory segments, but it did not canonicalize dot segments, duplicate slashes, encoded dots, or backslashes before route matching and before delegating to the send layer. As a result, an unauthenticated attacker could request a file protected by a route based guard using a non canonical path form that misses the guarded route yet resolves back onto the protected file, disclosing its contents. Applications that protect a subtree of the static root with a route based guard are affected, while applications relying on the allowedPath option are not. This is fixed in @fastify/static 10.1.3, which canonicalizes the pathname, including rejecting backslashes, on the path used for routing and serving. | |
| Title | @fastify/static vulnerable to route guard bypass via non-canonical path segments | |
| Weaknesses | CWE-22 CWE-436 |
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| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: openjs
Published:
Updated: 2026-08-06T14:52:26.958Z
Reserved: 2026-07-30T18:18:39.071Z
Link: CVE-2026-18427
Updated: 2026-08-06T15:44:51.874Z
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OpenCVE Enrichment
Updated: 2026-08-06T16:45:07Z