CVE-2026-33805

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.

References

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33805.json

https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74-vj37

https://cna.openjsf.org/security-advisories.html

https://bugzilla.redhat.com/show_bug.cgi?id=2458651

https://access.redhat.com/security/cve/CVE-2026-33805

https://access.redhat.com/errata/RHSA-2026:10175

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4

EPSS