CVE-2026-85184: critical vulnerability in @fastify/middie
@fastify/middie vulnerable to path-scoped middleware bypass via absolute-form request target
Published
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28Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 9.1epss 0.5%
@fastify/middie versions >= 9.1.0 and before 9.3.4 decide whether to run path-scoped middleware by matching against the raw request target, while the Fastify router resolves an absolute-form request target to its path before dispatching. Because the two layers evaluate different strings, a request using an absolute-form target reaches the route handler while the path-scoped middleware, such as authentication or authorization, is skipped. An unauthenticated network attacker can use this to bypass path-based access controls in a Fastify application that relies on middie for those controls. Users should upgrade to @fastify/middie 9.3.4 or later.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Affected products
@fastify/middie · @fastify/middieRelated CVEs — @fastify/middie
In the same product, most dangerous first.
CVE-2026-14198CRITICAL@fastify/middie vulnerable to authorization bypass via encoded slash in path parameter valuesEPSS 0.5%CVE-2026-14181HIGH@fastify/middie standalone engine vulnerable to Denial of Service via malformed percent-encoded pathsEPSS 0.5%CVE-2026-6270CRITICAL@fastify/middie vulnerable to middleware authentication bypass in child plugin scopesEPSS 0.5%CVE-2026-2880HIGH@fastify/middie has an improper path normalization vulnerabilityEPSS 0.4%CVE-2026-112712CRITICAL@fastify/middie vulnerable to path-scoped middleware bypass via scope prefix mismatchEPSS 0.3%CVE-2026-33804HIGH@fastify/middie vulnerable to middleware bypass via deprecated ignoreDuplicateSlashes optionEPSS 0.3%