CVE-2026-32305Public exploitNetwork attack vector

mTLS bypass via incomplete ClientHello SNI parsing

Published Mar 20, 2026 · Updated Mar 20, 2026

Authentication bypass in Traefik Proxy allows remote attackers to access mTLS-protected services via a fragmented TLS ClientHello. The clientHelloInfo helper in router.go reads only the first TLS record, treats an incomplete parse as an empty SNI, and selects the default TLS policy. Exploitation requires route-level mTLS plus a weaker default TLS configuration; the unauthenticated connection then reaches the protected service.

CVSS severity7.8
High
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Traefik Proxy allows remote attackers to access mTLS-protected services via a fragmented TLS ClientHello. The clientHelloInfo helper in router.go reads only the first TLS record, treats an incomplete parse as an empty SNI, and selects the default TLS policy. Exploitation requires route-level mTLS plus a weaker default TLS configuration; the unauthenticated connection then reaches the protected service.

The record

CVE
CVE-2026-32305
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
Traefik Labs
Product
Traefik Proxy
Classifications
CWE-287, CWE-1188, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.11.41
  2. Affected versionversion=>= 3.0.0-beta1, < 3.6.11
  3. Affected versionversion=>= 3.7.0-ea.1, < 3.7.0-ea.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Traefik Labs · Traefik Proxyversion=< 2.11.41; version=>= 3.0.0-beta1, < 3.6.11; version=>= 3.7.0-ea.1, < 3.7.0-ea.2

Published CVSS scores

7.8GitHub, Inc.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
5.3NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
8.3Red Hat Product SecurityCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-287Improper Authentication
CWE-1188Insecure Default Initialization of Resource
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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