CVE catalog
CVE-2026-39858
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 a high severity authentication bypass vulnerability in Traefik's ForwardAuth and snippet
- Severity
- Critical · CVSS 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.48% · Oct 25, 2026
A flaw was found in Traefik. A remote attacker can exploit an authentication bypass vulnerability by injecting spoofed trust context through unsanitized alias headers. This is due to Traefik's forwarded-header sanitization logic not properly handling alias header names that use underscores instead of dashes. This allows an attacker to bypass authentication on protected routes without valid credentials. traefik: Traefik: Authentication bypass via unsanitized alias headers The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Cpe | traefik | Not reported | 2.11.43 | fixed |
| Cpe | traefik | Not reported | 3.6.14 | fixed |
| Cpe | traefik | Not reported | Not reported | unknown |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Cpe | traefik | cpe | Not reported | 2.11.43 | Not reported | Not reported | Not reported |
| Cpe | traefik | cpe | Not reported | 3.6.14 | Not reported | Not reported | Not reported |
OpenFactory catalog packages
No matching packages in this catalog.
Observed:
References
- [https://ftp.suse.com/pub/projects/security/csaf/opensuse-su-2026_10697-1.json]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-39858]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-39858.json]
[FIRST EPSS] · [National Vulnerability Database (NVD)] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]