CVE-2026-33805

@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.

CVSS v3 8.6 HIGH

8.6^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 4.0

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact HIGH

Availability Impact NONE

Scope CHANGED

References

Link	Resource
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

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:fastify:fastify\/http-proxy::::::node.js::*
	cpe:2.3:a:fastify:reply-from::::::node.js::*

History

No history.

Information

Published : 2026-04-15 11:16

Updated : 2026-07-15 02:20

NVD link : CVE-2026-33805

Mitre link : CVE-2026-33805

CVE.ORG link : CVE-2026-33805

JSON object : View

Products Affected

fastify

fastify\/http-proxy
reply-from

CWE

CWE-644

Improper Neutralization of HTTP Headers for Scripting Syntax

CWE-444

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

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