EUVD-2026-22877
GHSA-gwhp-pf74-vj37
CVSS VectorNVD
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
1DescriptionNVD
@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.
AnalysisAI
Header smuggling in @fastify/reply-from (≤12.6.1) and @fastify/http-proxy (≤11.4.3) allows remote unauthenticated attackers to strip proxy-added security headers by manipulating the Connection header, bypassing access controls and routing policies. Affected deployments using these Node.js packages as reverse proxies face immediate risk of authentication bypass and security control evasion. …
Sign in for full analysis, threat intelligence, and remediation guidance.
RemediationAI
Within 24 hours: Identify all deployments using @fastify/reply-from ≤12.6.1 or @fastify/http-proxy ≤11.4.3 via dependency audit (npm list or yarn list). Within 7 days: Implement network segmentation to restrict direct attacker access to affected proxy instances and enable request logging on all proxied traffic. …
Sign in for detailed remediation steps.
Share
External POC / Exploit Code
Leaving vuln.today