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Vulnerability record · CVE-2026-32305 · published 20 March 2026

CVE-2026-32305: Traefik improper authentication vulnerability

Traefik · Traefik

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.

7.8 CVSS 4.0 High EPSS 0.47% · top 61.6% CWE-287 · Improper authenticationCWE-1188 · Insecure default initialization
7.8CVSS 4.0 base score
0.47%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
9References
15 Jul 2026Last modified by NVD

Description

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.

CVSS:4.0/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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/traefik/traefik/releases/tag/v2.11.41 Release Notes
https://github.com/traefik/traefik/releases/tag/v3.6.11 Release Notes
https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.2 Release Notes
https://github.com/traefik/traefik/security/advisories/GHSA-wvvq-wgcr-9q48 PatchVendor Advisory
https://access.redhat.com/errata/RHSA-2026:10175
https://access.redhat.com/errata/RHSA-2026:21772
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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-32305), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.