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TI-2026-39569 Aliases CVE-2026-54763GHSA-x677-9fxg-v5c5

Traefik: headerField underscore-variant identity spoofing in BasicAuth / DigestAuth / ForwardAuth

Priority MEDIUM 40CWE-178Published · Updated

Key facts

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

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-290.

Summary

Traefik is an HTTP reverse proxy and load balancer. Prior to v2.11.51, v3.6.22, and v3.7.6, Traefik's BasicAuth, DigestAuth, and ForwardAuth middlewares strip canonical-cased spoofed identity headers before writing Traefik's own value, but do not account for underscore-variant header names, which many backends normalize identically to dashed forms. An attacker able to reach a protected route can inject an underscore-variant header that survives Traefik's stripping and reaches the backend alongside, or on the unauthenticated ForwardAuth authResponseHeaders path instead of, the value Traefik intended to set, spoofing identity or authorization context. This issue is fixed in versions v2.11.51, v3.6.22, and v3.7.6.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00239 15th percentileScored 2026-11-07
Fix Fixed traefik (traefik): 2.11.51, 3.6.22, 3.7.6github.com/traefik/traefik/v2 (Go): 2.11.51+1 more productRed Hat: 1 advisory

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
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
traefiktraefikbefore 2.11.51; 3.0.0-beta1 to before 3.6.22; 3.7.0-ea.1 to before 3.7.62.11.51, 3.6.22, 3.7.6Patch availableCNA
—github.com/traefik/traefik/v2 (Go)before 2.11.512.11.51Patch availableGHSA-x677-9fxg-v5c5
—github.com/traefik/traefik/v3 (Go)before 3.6.223.6.22Patch availableGHSA-x677-9fxg-v5c5
—github.com/traefik/traefik/v3 (Go)3.7.0 to before 3.7.63.7.6Patch availableGHSA-x677-9fxg-v5c5
  • traefik Vendortraefik Affected before 2.11.51; 3.0.0-beta1 to before 3.6.22; 3.7.0-ea.1 to before 3.7.6 Fixed in 2.11.51, 3.6.22, 3.7.6 Patch available CNA
  • github.com/traefik/traefik/v2 (Go) Vendor— Affected before 2.11.51 Fixed in 2.11.51 Patch available GHSA-x677-9fxg-v5c5
  • github.com/traefik/traefik/v3 (Go) Vendor— Affected before 3.6.22 Fixed in 3.6.22 Patch available GHSA-x677-9fxg-v5c5
  • github.com/traefik/traefik/v3 (Go) Vendor— Affected 3.7.0 to before 3.7.6 Fixed in 3.7.6 Patch available GHSA-x677-9fxg-v5c5

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*before 2.11.51; 3.0.0 to before 3.6.22; 3.7.0 to before 3.7.6Vulnerabletraefik
  • cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:* Versions before 2.11.51; 3.0.0 to before 3.6.22; 3.7.0 to before 3.7.6 Vulnerable ·traefik

Remediation

  • Fix · CNA traefik (traefik) Fixed in 2.11.51, 3.6.22, 3.7.6
  • Fix · GHSA-x677-9fxg-v5c5 github.com/traefik/traefik/v2 (Go) Fixed in 2.11.51 Advisory →
  • Fix · GHSA-x677-9fxg-v5c5 github.com/traefik/traefik/v3 (Go) Fixed in 3.6.22 Advisory →
  • Fix · GHSA-x677-9fxg-v5c5 github.com/traefik/traefik/v3 (Go) Fixed in 3.7.6 Advisory →

Red Hat 1 advisory

  • RHSA-2026:62260 Released 2026-09-01 · Red Hat rating Important
    Red Hat OpenShift Dev Spaces 3.30.0 Release.
    • Red Hat OpenShift Dev Spaces 3.30 registry.redhat.io/devspaces/code-rhel9, registry.redhat.io/devspaces/configbump-rhel9, registry.redhat.io/devspaces/dashboard-rhel9 +7

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Red Hat OpenShift Dev Spaces 3.30Fixed RHSA-2026:62260
Not affected: 1 product
  • Red Hat OpenShift Dev Spaces 3.30

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-54763
  2. 2026-10-03 Alias added: GHSA-x677-9fxg-v5c5

References

Patch 2

Advisory 1

Other 5

  • TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
  • TI-2023-25774 Uncontrolled Resource Consumption in Traefik CVSS 3.1HIGH 7.5
  • TI-2025-40914 Traefik doesn't Prevent Path Normalization Bypass in Router + Middleware Rules CVSS 4.0MEDIUM 6.9
  • TI-2022-07529 Authorization header displayed in the debug logs CVSS 3.1MEDIUM 6.5
  • TI-2024-30459 HTTP client can remove the X-Forwarded headers in Traefik CVSS 3.1CRITICAL 9.8
  • TI-2026-60261 Traefik v3.7.0 Authentication Bypass via from-to-www-redirect CVSS 4.0CRITICAL 9.3
See all 83 →

Sources

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