@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.
Fix
Patch, vendor advisory and mitigation references on NVD 3
- https://cna.openjsf.org/security-advisories.html Vendor Advisory
- https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74-vj37 Exploit, Mitigation, Vendor Advisory
- https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74-vj37 Exploit, Mitigation, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 9.0 · fastifyNVD modified 2026-10-26 22:10
Affected (CPE criteria) 2
cpe:2.3:a:fastify:fastify\/http-proxy:*:*:*:*:*:node.js:*:*cpe:2.3:a:fastify:reply-from:*:*:*:*:*:node.js:*:*
References 7
- https://cna.openjsf.org/security-advisories.html Vendor Advisory
- https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74-vj37 Exploit, Mitigation, Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:10175
- https://access.redhat.com/security/cve/CVE-2026-33805
- https://bugzilla.redhat.com/show_bug.cgi?id=2458651
- https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74-vj37 Exploit, Mitigation, Vendor Advisory
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33805.json