Interpretation Conflict Affecting @fastify/middie package, versions <9.2.0
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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- published1 Mar 2026
- disclosed27 Feb 2026
- creditUnknown
Introduced: 27 Feb 2026
CVE-2026-2880 (opens in a new tab)How to fix?
Upgrade @fastify/middie to version 9.2.0 or higher.
Overview
@fastify/middie is a Middleware engine for Fastify
Affected versions of this package are vulnerable to Interpretation Conflict via the middleware matching engine when router options like ignoreDuplicateSlashes, useSemicolonDelimiter, or other trailing-slash normalization are enabled. An attacker can bypass path-scoped authorization middleware and reach protected handlers by sending crafted normalized variants such as //secret, /secret;foo=bar, or /secret/.