CVE-2026-33805
HIGHCVSS v3.1: 8.6 · EPSS: 0.0033 (24.7 percentile)
Source data as of:
At a glance
- Severity
- HIGH
- CVSS
- 8.6 v3.1 · NVD
- EPSS
- 0.0033 (24.7 percentile) · FIRST.org
- CISA KEV
- No
- Attack conditions (CVSS vector)
- NetworkNo privilegesNo user interaction · Source: NVD Vector
- Affected vendors
- fastify
- Published
- 2026-04-15 · Modified: 2026-06-30
- References
- Jump to references (6)
CVSS / EPSS / KEV
Source — CVSS: NVD · EPSS: FIRST.org · KEV: CISA. Data & Sources
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
Reference URLs as listed by NVD, grouped by a mechanical match on the link's host/pattern. Labels describe the link type only.
- Vendor advisory https://cna.openjsf.org/security-advisories.html
- Vendor advisory https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74-vj37
- Distro https://access.redhat.com/errata/RHSA-2026:10175
- Distro https://access.redhat.com/security/cve/CVE-2026-33805
- Distro https://bugzilla.redhat.com/show_bug.cgi?id=2458651
- Distro https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33805.json