VDB
CVE-2026-33805
CVE-2026-33805
PUBLISHED
CVSS 9 CRITICAL
@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.
EPSS 0.02% · 4.1th percentile
Risk Scores
CVSS 4.0
9
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:H/SA:N
EPSS Score
0.02%
4.1th percentile
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| @fastify/reply-from | @fastify/reply-from | 12.6.2, 0 |
| @fastify/reply-from | @fastify/http-proxy | 0, 11.4.4 |
Exploit Intelligence
- https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74-vj37 (cve.org)
- CIRCL seen: CVE-2026-33805 (circl-sighting)
- CIRCL seen: CVE-2026-33805 (circl-sighting)
- https://cna.openjsf.org/security-advisories.html (circl)
Timeline
- Apr 15, 2026 CVE Published
- Apr 15, 2026 PoC Published
- Apr 15, 2026 PoC Published
- Apr 16, 2026 Security Advisory
- May 18, 2026 EPSS Score
- May 19, 2026 EPSS Score
- May 20, 2026 EPSS Score
- May 21, 2026 EPSS Score
- May 22, 2026 EPSS Score
- May 23, 2026 EPSS Score
- May 24, 2026 EPSS Score
- May 25, 2026 EPSS Score