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VULNERABILITIES

CVE-2026-33805 Details

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.

Metrics

CVSS 3.x Severity and Vector Strings:

NIST: [email protected]CVSS-B:8.6 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
CNA: redhat-SADPCVSS-B:7.4 HIGHVector:CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

References to Advisories, Solutions, and Tools

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URLSource(s)Tag(s)
https://access.redhat.com/errata/RHSA-2026:10175 redhat-SADP
https://access.redhat.com/security/cve/CVE-2026-33805 redhat-SADP
https://bugzilla.redhat.com/show_bug.cgi?id=2458651 redhat-SADP
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33805.json redhat-SADP
https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74-vj37 CISA-ADPExploitMitigationVendor Advisory

see all 7 references

Weakness Enumeration

CWE-IDCWE NameSource
CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')redhat-SADP
CWE-644Improper Neutralization of HTTP Headers for Scripting Syntaxopenjs

Affected Products

ProductVersions
fastify fastify/http-proxy
< 11.4.4

CPE

  • cpe:2.3:a:fastify:fastify/http-proxy:*:*:*:*:*:node.js:*:*

Remediation

  • No remediation found in references.
fastify reply-from
< 12.6.2

CPE

  • cpe:2.3:a:fastify:reply-from:*:*:*:*:*:node.js:*:*

Remediation

  • No remediation found in references.

Change History

7 change records found show changes

QUICK INFO

CVE Dictionary Entry:
CVE-2026-33805
NVD Published Date:
Apr 15, 2026
NVD Last Modified:
Jul 15, 2026
Source:
openjs
CVE-2026-33805 Details - Not Deferred