Upstream information
Description
Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.56, and from 3.0.0 until 3.7.12, a client-supplied dot-form header such as X.Authenticated.User survives ForwardAuth replacement and underscoreHeadersStrategy because Go treats it as distinct from X-Authenticated-User while normalization-prone CGI, WSGI, PHP, and NGINX backends collapse both names. A backend can consequently consume the client value instead of the identity Traefik asserted, allowing identity spoofing for any header managed by Traefik. The aliasHeadersStrategy protection is disabled by default and must be configured as delete or reject. The mitigation is available in 2.11.56 and 3.7.12.SUSE information
Overall state of this security issue: Resolved
This issue is currently rated as having important severity.
| CVSS detail | National Vulnerability Database |
|---|---|
| Base Score | 8.1 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N |
| Attack Vector | Network |
| Attack Complexity | Low |
| Privileges Required | Low |
| User Interaction | None |
| Scope | Unchanged |
| Confidentiality Impact | High |
| Integrity Impact | High |
| Availability Impact | None |
| CVSSv3 Version | 3.1 |
| CVSS detail | CNA (GitHub) |
|---|---|
| Base Score | 5.3 |
| Vector | CVSS:4.0/AV:N/AC:L/AT:P/PR:L/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 |
| Attack Vector | Network |
| Attack Complexity | Low |
| Attack Requirements | Present |
| Privileges Required | Low |
| User Interaction | None |
| Vulnerable System Confidentiality Impact | None |
| Vulnerable System Integrity Impact | None |
| Vulnerable System Availability Impact | None |
| Subsequent System Confidentiality Impact | High |
| Subsequent System Integrity Impact | High |
| Subsequent System Availability Impact | None |
| CVSSv4 Version | 4.0 |
SUSE Security Advisories:
- SUSE-SU-2026:23855-1, published 2026-09-21T12:26:05Z
- SUSE-SU-2026:23863-1, published 2026-09-21T12:36:27Z
List of released packages
| Product(s) | Fixed package version(s) | References |
|---|
SUSE Timeline for this CVE
CVE page created: Mon Sep 21 16:54:48 2026CVE page last modified: Fri Sep 25 12:55:34 2026