CVE-2026-85597
Traefik before v2.11.55 and v3.0.0 through v3.7.10 mTLS Bypass via TLS Option Conflict
Description
Traefik before v2.11.55 and v3.0.0 through v3.7.10 contain a TLS option conflict resolution vulnerability that allows unauthenticated attackers to bypass client-certificate authentication by creating conflicting TLS options on multi-host routers. Attackers can reach protected backends by exploiting shared TLS resolution across multiple hostnames in a single router rule, causing the strict mTLS requirement to fall back to default options for all hosts.
INFO
Published Date :
Sept. 4, 2026, 12:17 p.m.
Last Modified :
Sept. 16, 2026, 8:42 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 | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update Traefik to version 2.11.55 or later.
- Review and reconfigure TLS options for multi-host routers.
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-2026-85597.
| URL | Resource |
|---|---|
| https://github.com/traefik/traefik/security/advisories/GHSA-g55h-rg46-x9c5 | Exploit Mitigation Patch Vendor Advisory |
| https://www.vulncheck.com/advisories/traefik-before-2.11.55-mtls-bypass-via-tls-option-conflict | Third Party 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-2026-85597 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-2026-85597
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-2026-85597 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-85597 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.
-
Initial Analysis by [email protected]
Sep. 16, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Added CPE Configuration OR *cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:* versions up to (excluding) 2.11.55 *cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:* versions from (including) 3.0.0 up to (excluding) 3.7.11 Added Reference Type VulnCheck: https://github.com/traefik/traefik/security/advisories/GHSA-g55h-rg46-x9c5 Types: Exploit, Mitigation, Patch, Vendor Advisory Added Reference Type VulnCheck: https://www.vulncheck.com/advisories/traefik-before-2.11.55-mtls-bypass-via-tls-option-conflict Types: Third Party Advisory -
CVE Modified by [email protected]
Sep. 05, 2026
Action Type Old Value New Value Changed Description Traefik before v2.11.55 contains a TLS option conflict resolution vulnerability that allows unauthenticated attackers to bypass client-certificate authentication by creating conflicting TLS options on multi-host routers. Attackers can reach protected backends by exploiting shared TLS resolution across multiple hostnames in a single router rule, causing the strict mTLS requirement to fall back to default options for all hosts. Traefik before v2.11.55 and v3.0.0 through v3.7.10 contain a TLS option conflict resolution vulnerability that allows unauthenticated attackers to bypass client-certificate authentication by creating conflicting TLS options on multi-host routers. Attackers can reach protected backends by exploiting shared TLS resolution across multiple hostnames in a single router rule, causing the strict mTLS requirement to fall back to default options for all hosts. Added Affected Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/85xxx/CVE-2026-85597.json">CVE-2026-85597</a> -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 04, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-85597', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-09-04T18:03:53.030722Z'} -
New CVE Received by [email protected]
Sep. 04, 2026
Action Type Old Value New Value Added Description Traefik before v2.11.55 contains a TLS option conflict resolution vulnerability that allows unauthenticated attackers to bypass client-certificate authentication by creating conflicting TLS options on multi-host routers. Attackers can reach protected backends by exploiting shared TLS resolution across multiple hostnames in a single router rule, causing the strict mTLS requirement to fall back to default options for all hosts. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/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-863 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/85xxx/CVE-2026-85597.json">CVE-2026-85597</a> Added Reference https://github.com/traefik/traefik/security/advisories/GHSA-g55h-rg46-x9c5 Added Reference https://www.vulncheck.com/advisories/traefik-before-2.11.55-mtls-bypass-via-tls-option-conflict