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CVE

CVE-2026-33805

@fastify/reply-from vulnerable to connection header abuse enabling stripping of proxy-added headers
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CVE

CVE-2026-33805

@fastify/reply-from vulnerable to connection header abuse enabling stripping of proxy-added headers

@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.

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
9
-
4.0
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
C
H
U
0
-
C
H
U
-

Related Resources

No items found.

References

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33805.json, https://access.redhat.com/errata/RHSA-2026:10175, https://access.redhat.com/security/cve/CVE-2026-33805, https://cna.openjsf.org/security-advisories.html, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33805.json, https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74-vj37, https://nvd.nist.gov/vuln/detail/CVE-2026-33805, https://bugzilla.redhat.com/show_bug.cgi?id=2458651

Severity

0

CVSS Score
0
10

Basic Information

Base CVSS
0
EPSS Probability
0.00441%
EPSS Percentile
0.3663%
Introduced Version
0
Fix Available
15df3dc5eca55e2e61dba1745f422690b4a55257,457ac75f38bc846e8ab76a7cb1618d6c257b7fa2

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