Vulnerability Description
@fastify/reply-from v12.6.1 and earlier and @fastify/http-proxy v11.4.3 and earlier process the client's Connection header after the proxy has added its own headers via rewriteRequestHeaders. This allows attackers to retroactively strip proxy-added headers from upstream requests by listing them in the Connection header value. Any header added by the proxy for routing, access control, or security purposes can be selectively removed by a client. @fastify/http-proxy is also affected as it delegates to @fastify/reply-from. Upgrade to @fastify/reply-from v12.6.2 or @fastify/http-proxy v11.4.4 or later.
Related Weaknesses (CWE)
References
- https://cna.openjsf.org/security-advisories.html
- https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74
- https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74
FAQ
What is CVE-2026-33805?
CVE-2026-33805 is a documented vulnerability. @fastify/reply-from v12.6.1 and earlier and @fastify/http-proxy v11.4.3 and earlier process the client's Connection header after the proxy has added its own headers via rewriteRequestHeaders. This all...
How severe is CVE-2026-33805?
CVSS scoring is not yet available for CVE-2026-33805. Check NVD for updates.
Is there a patch for CVE-2026-33805?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.