Traefik Vulnerable to BasicAuth/DigestAuth Identity Spoofing via Non-Canonical headerField
Summary
| CVE | CVE-2026-33433 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_M |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-03-27 15:16:54 UTC |
| Updated | 2026-07-15 02:20:13 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v4.0 5.1 MEDIUM from [email protected]
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/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
EPSS: 0.000200000 probability, percentile 0.053590000 (date 2026-04-06)
Problem Types: CWE-290 | CWE-290 CWE-290: Authentication Bypass by Spoofing | CWE-290 Authentication Bypass by Spoofing
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 5.1 | MEDIUM | CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/C... |
| 4.0 | CNA | DECLARED | 5.1 | MEDIUM | CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N |
| 3.1 | [email protected] | Primary | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | ADP | CVSS | 7.7 | HIGH | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:N |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 7.7 | HIGH | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:N |
CVSS v4.0 Breakdown
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/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
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD Known Affected Configurations (CPE 2.3)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Traefik | Traefik | affected < 2.11.42 | Not specified |
| CNA | Traefik | Traefik | affected >= 3.0.0-beta1, < 3.6.11 | Not specified |
| CNA | Traefik | Traefik | affected >= 3.7.0-ea.1, < 3.7.0-ea.3 | Not specified |
| ADP | Red Hat | Red Hat OpenShift Dev Spaces 3.27 | unaffected 1776718585 * rpm | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | |
| github.com/traefik/traefik/releases/tag/v3.6.11 | [email protected] | github.com | Product, Release Notes |
| github.com/traefik/traefik/releases/tag/v2.11.42 | [email protected] | github.com | Product, Release Notes |
| access.redhat.com/security/cve/CVE-2026-33433 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| github.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7c | [email protected] | github.com | Exploit, Patch, Vendor Advisory |
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33433.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| github.com/traefik/traefik/releases/tag/v3.7.0-ea.3 | [email protected] | github.com | Product, Release Notes |
| access.redhat.com/errata/RHSA-2026:10175 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| 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 | 2026-03-27T15:03:19.672Z | Reported to Red Hat. |
| ADP | 2026-03-27T13:49:08.455Z | Made public. |
Solutions
ADP: RHSA-2026:10175: Red Hat OpenShift Dev Spaces 3.27
Workarounds
ADP: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.