Interpretation Conflict Affecting @fastify/middie package, versions >=9.0.0 <9.3.6
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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- published22 Oct 2026
- disclosed20 Oct 2026
- creditZachariah Mithani
Introduced: 20 Oct 2026
NewCVE-2026-112712 (opens in a new tab)How to fix?
Upgrade @fastify/middie to version 9.3.6 or higher.
Overview
@fastify/middie is a Middleware engine for Fastify
Affected versions of this package are vulnerable to Interpretation Conflict via incorrect prefix-path joining in the use function, where middleware mount paths are concatenated with the Fastify route prefix using a logic that diverges from Fastify's own route joining rules. An attacker can send requests to paths that should be protected by middleware but are not matched due to the malformed joined path, effectively bypassing middleware-enforced controls such as authentication or authorization.