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High 8.2Published Feb 27, 2026

CVE-2026-2880@fastify/middie has an improper path normalization vulnerability

Updated under an hour ago ()

Does this affect you?

It affects @fastify/middie and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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.

CVSS
8.2 HIGH (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness (CWE)
CWE-20
Known exploited
Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days)
Not loaded for this CVE
Assigned by
openjs
NVD analysis
Analyzed
Record last updated
Feb 27, 2026
First seen by InfoSec Signals
Oct 9, 2026

Affected products

Affected products
@fastify/middie @fastify/middie
fastify_middie:fastify_middie (from the name)
from 0.0.0 before 9.2.0
CNA record
fastify fastify/middie
fastify:fastify/middie
before 9.2.0
NVD

References

References

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.

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CVE-2026-2880: @fastify/middie has an improper path normalization vulnerability | InfoSec Signals