CVE-2026-54763
Traefik: headerField underscore-variant identity spoofing in BasicAuth / DigestAuth / ForwardAuth
Description
Traefik is an HTTP reverse proxy and load balancer. Prior to v2.11.51, v3.6.22, and v3.7.6, Traefik's BasicAuth, DigestAuth, and ForwardAuth middlewares strip canonical-cased spoofed identity headers before writing Traefik's own value, but do not account for underscore-variant header names, which many backends normalize identically to dashed forms. An attacker able to reach a protected route can inject an underscore-variant header that survives Traefik's stripping and reaches the backend alongside, or on the unauthenticated ForwardAuth authResponseHeaders path instead of, the value Traefik intended to set, spoofing identity or authorization context. This issue is fixed in versions v2.11.51, v3.6.22, and v3.7.6.
INFO
Published Date :
July 6, 2026, 9:16 p.m.
Last Modified :
July 8, 2026, 8:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update Traefik to v2.11.51 or later.
- Update Traefik to v3.6.22 or later.
- Update Traefik to v3.7.6 or later.
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-2026-54763.
| URL | Resource |
|---|---|
| https://github.com/traefik/traefik/commit/108a5264473a2cbc8f12d6d691a3c6553cdf2c1b | Patch |
| https://github.com/traefik/traefik/pull/13262 | Issue Tracking |
| https://github.com/traefik/traefik/security/advisories/GHSA-x677-9fxg-v5c5 | Patch Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-54763 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-2026-54763
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-2026-54763 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-54763 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.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 08, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-54763', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-08T17:13:29.094037Z'} -
Initial Analysis by [email protected]
Jul. 08, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N Added CPE Configuration OR *cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:* versions from (including) 3.7.0 up to (excluding) 3.7.6 *cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:* versions up to (excluding) 2.11.51 *cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:* versions from (including) 3.0.0 up to (excluding) 3.6.22 Added Reference Type GitHub, Inc.: https://github.com/traefik/traefik/commit/108a5264473a2cbc8f12d6d691a3c6553cdf2c1b Types: Patch Added Reference Type GitHub, Inc.: https://github.com/traefik/traefik/pull/13262 Types: Issue Tracking Added Reference Type GitHub, Inc.: https://github.com/traefik/traefik/security/advisories/GHSA-x677-9fxg-v5c5 Types: Patch, Vendor Advisory -
CVE Modified by [email protected]
Jul. 07, 2026
Action Type Old Value New Value Changed Affected [{'vendor': 'traefik', 'product': 'traefik', 'versions': [{'status': 'affected', 'version': '< 2.11.51'}, {'status': 'affected', 'version': '>= 3.0.0-beta1, < v3.6.22'}, {'status': 'affected', 'version': '>= 3.7.0-ea.1, < v3.7.6'}]}] [{'vendor': 'traefik', 'product': 'traefik', 'versions': [{'status': 'affected', 'version': '< 2.11.51'}, {'status': 'affected', 'version': '>= 3.0.0-beta1, < 3.6.22'}, {'status': 'affected', 'version': '>= 3.7.0-ea.1, < 3.7.6'}]}] -
New CVE Received by [email protected]
Jul. 06, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'traefik', 'product': 'traefik', 'versions': [{'status': 'affected', 'version': '< 2.11.51'}, {'status': 'affected', 'version': '>= 3.0.0-beta1, < v3.6.22'}, {'status': 'affected', 'version': '>= 3.7.0-ea.1, < v3.7.6'}]}] Added Description Traefik is an HTTP reverse proxy and load balancer. Prior to v2.11.51, v3.6.22, and v3.7.6, Traefik's BasicAuth, DigestAuth, and ForwardAuth middlewares strip canonical-cased spoofed identity headers before writing Traefik's own value, but do not account for underscore-variant header names, which many backends normalize identically to dashed forms. An attacker able to reach a protected route can inject an underscore-variant header that survives Traefik's stripping and reaches the backend alongside, or on the unauthenticated ForwardAuth authResponseHeaders path instead of, the value Traefik intended to set, spoofing identity or authorization context. This issue is fixed in versions v2.11.51, v3.6.22, and v3.7.6. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/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-345 Added CWE CWE-178 Added CWE CWE-290 Added Reference https://github.com/traefik/traefik/commit/108a5264473a2cbc8f12d6d691a3c6553cdf2c1b Added Reference https://github.com/traefik/traefik/pull/13262 Added Reference https://github.com/traefik/traefik/security/advisories/GHSA-x677-9fxg-v5c5