Improper Handling of Case Sensitivity Affecting @fastify/static package, versions <10.1.4
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-FASTIFYSTATIC-19883910
- published17 Sept 2026
- disclosed17 Sept 2026
- credit0xRenSec
Introduced: 17 Sep 2026
NewCVE-2026-90982 (opens in a new tab)How to fix?
Upgrade @fastify/static to version 10.1.4 or higher.
Overview
@fastify/static is a Plugin for serving static files as fast as possible.
Affected versions of this package are vulnerable to Improper Handling of Case Sensitivity via the route matching process. An attacker can access protected files by altering the letter case of a path segment in a request on case-insensitive filesystems, thereby bypassing route guard or allowedPath restrictions.
Note: This is only exploitable if the server is running on a case-insensitive filesystem such as Windows or the default macOS volume.
Workaround
This vulnerability can be mitigated by serving static files from a case-sensitive filesystem, or by ensuring route guards and allowedPath rules account for every letter-case variant of the protected paths.