CVE-2026-88011
Traefik: ForwardAuth identity spoofing via dot-form header alias
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.
INFO
Published Date :
Sept. 10, 2026, 4:18 p.m.
Last Modified :
Sept. 10, 2026, 4:18 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Traefik to version 2.11.56 or 3.7.12.
- Configure aliasHeadersStrategy to delete or reject.
- Restart Traefik services after applying changes.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-88011.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-88011 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-88011
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-88011 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-88011 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Sep. 10, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 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 Added CWE CWE-290 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/88xxx/CVE-2026-88011.json">CVE-2026-88011</a> Added Reference https://github.com/traefik/traefik/commit/0331801c72329e0eaeb850e53ccce87c57fbecf8 Added Reference https://github.com/traefik/traefik/pull/13720 Added Reference https://github.com/traefik/traefik/releases/tag/v2.11.56 Added Reference https://github.com/traefik/traefik/releases/tag/v3.7.12 Added Reference https://github.com/traefik/traefik/security/advisories/GHSA-rf44-j88r-hh8c