Is @fastify/express affected by CVE-2026-33808?

npm @fastify/express is affected in <4.0.5.

Is CVE-2026-33808 being exploited?

Not on the CISA KEV list. EPSS exploit probability is 0.5%.

critical

CVE-2026-33808

Q: Is CVE-2026-33808 being exploited?

Not on the CISA KEV list. EPSS exploit probability is 0.5%.

npm · @fastify/express

Summary

@fastify/express has a middleware authentication bypass via URL normalization gaps (duplicate slashes and semicolons)

Severity: critical
EPSS: 0.5% (p38)
Also known as: GHSA-6hw5-45gm-fj88
Published: 2026-04-16

References

https://github.com/fastify/fastify-express/security/advisories/GHSA-6hw5-45gm-fj88
https://nvd.nist.gov/vuln/detail/CVE-2026-33808
https://cna.openjsf.org/security-advisories.html

Related advisories

CVE-2026-33807 — critical · npm/@fastify/express

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Sources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.