Traefik Vulnerable to BasicAuth/DigestAuth Identity Spoofing via Non-Canonical headerField
Priority LOW 24CWE-290Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- Present
- 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 versions 2.11.42, 3.6.11, and 3.7.0-ea.3, when `headerField` is configured with a non-canonical HTTP header name (e.g., `x-auth-user` instead of `X-Auth-User`), an authenticated attacker can inject their own canonical version of that header to impersonate any identity to the backend. The backend receives two header entries — the attacker-injected canonical one is read first, overriding Traefik's non-canonical write. Versions 2.11.42, 3.6.11, and 3.7.0-ea.3 patch the issue.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00487 42nd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed traefik (traefik): 2.11.42, 3.6.11, 3.7.0-ea.3github.com/traefik/traefik/v2 (Go): 2.11.42+1 more productRed Hat: 1 advisory
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| traefik | traefik | before 2.11.42; 3.0.0-beta1 to before 3.6.11; 3.7.0-ea.1 to before 3.7.0-ea.3 | 2.11.42, 3.6.11, 3.7.0-ea.3 | Patch available | CNA |
| — | github.com/traefik/traefik/v2 (Go) | before 2.11.42 | 2.11.42 | Patch available | GHSA-qr99-7898-vr7c |
| — | github.com/traefik/traefik/v3 (Go) | 3.0.0-beta1 to before 3.6.12 | 3.6.12 | Patch available | GHSA-qr99-7898-vr7c |
| — | github.com/traefik/traefik/v3 (Go) | 3.7.0-ea.1 to before 3.7.0-ea.3 | 3.7.0-ea.3 | Patch available | GHSA-qr99-7898-vr7c |
- traefik Vendortraefik Affected before 2.11.42; 3.0.0-beta1 to before 3.6.11; 3.7.0-ea.1 to before 3.7.0-ea.3 Fixed in 2.11.42, 3.6.11, 3.7.0-ea.3 Patch available CNA
- github.com/traefik/traefik/v2 (Go) Vendor— Affected before 2.11.42 Fixed in 2.11.42 Patch available GHSA-qr99-7898-vr7c
- github.com/traefik/traefik/v3 (Go) Vendor— Affected 3.0.0-beta1 to before 3.6.12 Fixed in 3.6.12 Patch available GHSA-qr99-7898-vr7c
- github.com/traefik/traefik/v3 (Go) Vendor— Affected 3.7.0-ea.1 to before 3.7.0-ea.3 Fixed in 3.7.0-ea.3 Patch available GHSA-qr99-7898-vr7c
Remediation
- Fix · CNA traefik (traefik) Fixed in 2.11.42, 3.6.11, 3.7.0-ea.3
- Fix · GHSA-qr99-7898-vr7c github.com/traefik/traefik/v2 (Go) Fixed in 2.11.42 Advisory →
- Fix · GHSA-qr99-7898-vr7c github.com/traefik/traefik/v3 (Go) Fixed in 3.6.12 Advisory →
- Fix · GHSA-qr99-7898-vr7c github.com/traefik/traefik/v3 (Go) Fixed in 3.7.0-ea.3 Advisory →
Red Hat 1 advisory
- RHSA-2026:10175 Released 2026-04-23 · Red Hat rating ImportantRed 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 →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat OpenShift Dev Spaces 3.27 | Fixed | RHSA-2026:10175 |
Not affected: 1 product
- Red Hat OpenShift Dev Spaces 3.27
Timeline
- 2026-10-02 Threatist record created from CVE-2026-33433
- 2026-10-03 Alias added: GHSA-qr99-7898-vr7c
- 2026-11-04 CVSS score changed · GHSA-qr99-7898-vr7c
- 2026-11-04 4 new references · GHSA-qr99-7898-vr7c
References
Other 8
- https://github.com/traefik/traefik/releases/tag/v2.11.42
- https://github.com/traefik/traefik/releases/tag/v3.6.11
- https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3
- https://access.redhat.com/errata/RHSA-2026:10175
- https://access.redhat.com/security/cve/CVE-2026-33433
- https://bugzilla.redhat.com/show_bug.cgi?id=2452289
- https://github.com/traefik/traefik
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33433.json
More Traefik vulnerabilities
- 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
Sources
- CVE-2026-33433 · CVE Program
- CVE-2026-33433 · NVD
- FIRST EPSS
- GHSA-qr99-7898-vr7c · GitHub Advisory Database · CC BY 4.0
- CVE-2026-33433 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences