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TI-2026-26177 Aliases CVE-2026-33805GHSA-gwhp-pf74-vj37

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

Priority HIGH 78CWE-644Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
—
Confidentiality · integrity · availability
None · High · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat.

Summary

@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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00441 38th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed @fastify/reply-from (@fastify/reply-from): 12.6.2@fastify/http-proxy (@fastify/reply-from): 11.4.4+2 more productsRed Hat: 2 advisories

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
@fastify/reply-from@fastify/reply-frombefore 12.6.212.6.2Patch availableCNA
@fastify/reply-from@fastify/http-proxybefore 11.4.411.4.4Patch availableCNA
—@fastify/reply-from (npm)before 12.6.212.6.2Patch availableGHSA-gwhp-pf74-vj37
—@fastify/http-proxy (npm)before 11.4.411.4.4Patch availableGHSA-gwhp-pf74-vj37
  • @fastify/reply-from Vendor@fastify/reply-from Affected before 12.6.2 Fixed in 12.6.2 Patch available CNA
  • @fastify/http-proxy Vendor@fastify/reply-from Affected before 11.4.4 Fixed in 11.4.4 Patch available CNA
  • @fastify/reply-from (npm) Vendor— Affected before 12.6.2 Fixed in 12.6.2 Patch available GHSA-gwhp-pf74-vj37
  • @fastify/http-proxy (npm) Vendor— Affected before 11.4.4 Fixed in 11.4.4 Patch available GHSA-gwhp-pf74-vj37

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:fastify:fastify\/http-proxy:*:*:*:*:*:node.js:*:*before 11.4.4Vulnerablefastify
cpe:2.3:a:fastify:reply-from:*:*:*:*:*:node.js:*:*before 12.6.2Vulnerablefastify
  • cpe:2.3:a:fastify:fastify\/http-proxy:*:*:*:*:*:node.js:*:* Versions before 11.4.4 Vulnerable ·fastify
  • cpe:2.3:a:fastify:reply-from:*:*:*:*:*:node.js:*:* Versions before 12.6.2 Vulnerable ·fastify

Remediation

  • Fix · CNA @fastify/reply-from (@fastify/reply-from) Fixed in 12.6.2
  • Fix · CNA @fastify/http-proxy (@fastify/reply-from) Fixed in 11.4.4
  • Fix · GHSA-gwhp-pf74-vj37 @fastify/reply-from (npm) Fixed in 12.6.2 Advisory →
  • Fix · GHSA-gwhp-pf74-vj37 @fastify/http-proxy (npm) Fixed in 11.4.4 Advisory →

Red Hat 2 advisories

  • RHSA-2026:87410 Released 2026-10-21 · Red Hat rating Critical
    RHOAI 2.25.12 - Red Hat OpenShift AI
    • Red Hat OpenShift AI 2.25 registry.redhat.io/rhoai/odh-built-in-detector-rhel9, registry.redhat.io/rhoai/odh-caikit-nlp-rhel9, registry.redhat.io/rhoai/odh-codeflare-operator-rhel9 +47
  • RHSA-2026:10175 Released 2026-04-23 · Red Hat rating Important
    Red Hat OpenShift Dev Spaces 3.27.1 Release.
    • Red Hat OpenShift Dev Spaces 3.27 registry.redhat.io/devspaces/code-rhel9, registry.redhat.io/devspaces/dashboard-rhel9, registry.redhat.io/devspaces/devspaces-rhel9-operator +8

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat OpenShift AI 2.25Fixed RHSA-2026:87410
Red Hat OpenShift Dev Spaces 3.27Fixed RHSA-2026:10175
Not affected: 3 products
  • Red Hat OpenShift AI (RHOAI)
  • Red Hat OpenShift AI 2.25
  • Red Hat OpenShift Dev Spaces 3.27

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-33805
  2. 2026-10-03 Alias added: GHSA-gwhp-pf74-vj37
  3. 2026-10-22 Fix available: RHSA-2026:87410 · Red Hat
  4. 2026-10-23 Fix available: Red Hat OpenShift AI 2.25 · Red Hat

References

Exploit 1

Advisory 2

Other 1

  • TI-2026-83785 Path traversal in @fastify/reply-from via backslash dot-segments CVSS 3.1HIGH 8.2
  • TI-2026-69753 Improper certificate validation in @fastify/reply-from transports CVSS 3.1HIGH 7.4

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences