CVE-2026-32305
Published: 20 March 2026
Summary
CVE-2026-32305 is a high-severity Improper Authentication (CWE-287) vulnerability in Traefik Traefik. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 22.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-13663
Vulnerability details
Traefik is an HTTP reverse proxy and load balancer. Versions 2.11.40 and below, 3.0.0-beta1 through 3.6.11, and 3.7.0-ea.1 are vulnerable to mTLS bypass through the TLS SNI pre-sniffing logic related to fragmented ClientHello packets. When a TLS ClientHello is fragmented…
more
across multiple records, Traefik's SNI extraction may fail with an EOF and return an empty SNI. The TCP router then falls back to the default TLS configuration, which does not require client certificates by default. This allows an attacker to bypass route-level mTLS enforcement and access services that should require mutual TLS authentication. This issue is patched in versions 2.11.41, 3.6.11 and 3.7.0-ea.2.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Vulnerability in public-facing Traefik proxy enables direct bypass of mTLS authentication via crafted fragmented TLS ClientHello, matching T1190 Exploit Public-Facing Application.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Centralized authentication mechanisms and policy enforcement reduce the chance of missing or weak authentication on individual components.
Developer-provided instruction on authentication controls improves correct implementation and ongoing operation of authentication.
Detects unauthorized successful logons resulting from improper authentication implementations.
Documented procedures ensure personnel are trained on authentication mechanisms, tangibly lowering the risk of improper authentication being exploited.
Security awareness training instructs users on secure authentication practices and avoiding credential compromise.
Training on authentication mechanisms and best practices decreases the occurrence of improper authentication.
Non-repudiation requires strong authentication mechanisms to irrefutably attribute performed actions to specific individuals or processes.
Session content review can reveal authentication bypasses or failures in session establishment.