CVE-2026-32305

Summary

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 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.

Affected Software

Weaknesses

• CWE-287: CWE-287: Improper Authentication
• CWE-1188: CWE-1188: Insecure Default Initialization of Resource

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: yes
  • Technical Impact: partial

Traefik: github.com/traefik/traefik: Traefik: mTLS bypass allows unauthorized service access via fragmented ClientHello.

Additional References

• https://access.redhat.com/security/cve/CVE-2026-32305
• https://bugzilla.redhat.com/show_bug.cgi?id=2449595
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32305.json
• https://access.redhat.com/errata/RHSA-2026:10175
• https://access.redhat.com/errata/RHSA-2026:21772

References

• https://github.com/traefik/traefik/security/advisories/GHSA-wvvq-wgcr-9q48
• https://github.com/traefik/traefik/releases/tag/v2.11.41
• https://github.com/traefik/traefik/releases/tag/v3.6.11
• https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.2

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