Uncaught Exception Affecting @fastify/middie package, versions >=9.1.0 <9.3.3
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 Jul 2026
- disclosed1 Jul 2026
- creditJvr2022
Introduced: 1 Jul 2026
NewCVE-2026-14181 (opens in a new tab)How to fix?
Upgrade @fastify/middie to version 9.3.3 or higher.
Overview
@fastify/middie is a Middleware engine for Fastify
Affected versions of this package are vulnerable to Uncaught Exception in the URL normalization process when handling malformed percent-encoded sequences in incoming request paths. An attacker can cause the Node.js process to terminate unexpectedly by sending specially crafted requests with incomplete percent escapes or truncated multibyte sequences. This is only exploitable if the standalone engine API is used directly, as applications using the Fastify plugin path are not affected.
Workaround
This vulnerability can be mitigated by migrating from the standalone engine API to the Fastify plugin path, where the framework error handler catches the exception.