Traefik: ForwardAuth trustForwardHeader=false allows spoofed X-Forwarded-Prefix to bypass auth
Summary
| CVE | CVE-2026-35051 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_M |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-04-30 21:16:32 UTC |
| Updated | 2026-06-30 03:19:01 UTC |
| Description | Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is an authentication bypass vulnerability in Traefik's ForwardAuth middleware when trustForwardHeader=false is configured and Traefik is deployed behind a trusted upstream proxy. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2. |
Risk And Classification
Primary CVSS: v4.0 7.8 HIGH from [email protected]
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/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
EPSS: 0.000140000 probability, percentile 0.026910000 (date 2026-05-05)
Problem Types: CWE-345 | CWE-501 | CWE-345 CWE-345: Insufficient Verification of Data Authenticity | CWE-501 Trust Boundary Violation
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 7.8 | HIGH | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N/E:X/C... |
| 4.0 | CNA | DECLARED | 7.8 | HIGH | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N |
| 3.1 | [email protected] | Primary | 10 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N |
| 3.1 | ADP | CVSS | 8.2 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 8.2 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N |
CVSS v4.0 Breakdown
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/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
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
NVD Known Affected Configurations (CPE 2.3)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Traefik | Traefik | affected < 2.11.43 | Not specified |
| CNA | Traefik | Traefik | affected >= 3.0.0-beta1, < 3.6.14 | Not specified |
| CNA | Traefik | Traefik | affected >= 3.7.0-ea.1, < 3.7.0-rc.2 | Not specified |
| ADP | Red Hat | Red Hat OpenShift Dev Spaces 3.28 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/traefik/traefik/releases/tag/v2.11.43 | [email protected] | github.com | Product, Release Notes |
| access.redhat.com/security/cve/CVE-2026-35051 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | |
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-35051.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| github.com/traefik/traefik/releases/tag/v3.6.14 | [email protected] | github.com | Product, Release Notes |
| github.com/traefik/traefik/security/advisories/GHSA-6384-m2mw-rf54 | [email protected] | github.com | Exploit, Patch, Vendor Advisory |
| access.redhat.com/errata/RHSA-2026:21772 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| github.com/traefik/traefik/releases/tag/v3.7.0-rc.2 | [email protected] | github.com | Product, Release Notes |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| ADP | 2026-04-30T21:01:28.437Z | Reported to Red Hat. |
| ADP | 2026-04-30T20:26:06.716Z | Made public. |
Solutions
ADP: RHSA-2026:21772: Red Hat OpenShift Dev Spaces 3.28
Workarounds
ADP: To mitigate this issue, ensure that the `trustForwardHeader` setting in Traefik's ForwardAuth middleware is not explicitly configured as `false` unless absolutely necessary. If Traefik is deployed behind a trusted upstream proxy, review the configuration to ensure that `trustForwardHeader` is either set to `true` or omitted, allowing Traefik to correctly process forwarded headers for authentication. If this configuration is modified, a restart or reload of the Traefik service may be required for the changes to take effect.