Vulnerability Details CVE-2026-2880
A vulnerability in @fastify/middie versions < 9.2.0 can result in authentication/authorization bypass when using path-scoped middleware (for example, app.use('/secret', auth)).
When Fastify router normalization options are enabled (such as ignoreDuplicateSlashes, useSemicolonDelimiter, and related trailing-slash behavior), crafted request paths may bypass middleware checks while still being routed to protected handlers.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 37.5%
CVSS Severity
CVSS v3 Score 9.1
Products affected by CVE-2026-2880
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cpe:2.3:a:openjsf:@fastify/middie:*