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Fencer Intel
critical 9.1

CVE-2026-53622 json

Traefik: HTTP/3 mTLS bypass via exact SNI TLSOptions lookup for wildcard and mixed-case hosts

published 4mo ago modified 2mo ago also EUVD-2026-38576 , GHSA-9cr8-q42q-g8m7 , GO-2026-5287

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

Traefik is an HTTP reverse proxy and load balancer. Versions prior to 3.7.3, 3.6.18, and 2.11.51 have a critical vulnerability in Traefik's HTTP/3 (QUIC) TLS configuration selection that allows unauthenticated clients to bypass router-specific mTLS enforcement. When HTTP/3 is enabled on an entrypoint, the TLS handshake selects the applicable TLS configuration through an exact, case-sensitive lookup on the SNI value, which fails to match wildcard host patterns (e.g., *.example.com) or case variants of the configured hostname. Because the handshake falls back to the default TLS configuration — which may not require client certificates — a client can complete the QUIC handshake without presenting a certificate, while the subsequent HTTP routing layer still dispatches the request to a backend protected by a router-specific mTLS policy. The issue affects deployments where HTTP/3 is enabled, a router uses a wildcard Host rule or case-insensitive hostname matching, a router-specific TLSOptions enforces client certificate authentication, and UDP access to the entrypoint is reachable by an attacker. This vulnerability is fixed in versions 3.7.3, 3.6.18, and 2.11.51.

Patch / fix

  • go github.com/traefik/traefik/v3 3.6.18, 3.7.3
  • go github.com/traefik/traefik/v2 2.11.51
  • Red Hat Red Hat OpenShift Dev Spaces 3.30 1787756799
  • govulncheck-vulndb SLES for SAP applications 16.0, SLES 16.0 0.0.20260827T195228-160000.1.1

suse advisories SUSE-SU-2026:23625-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260827T195228-160000.1.1
  • traefik openSUSE Tumbleweed 3.7.5-1.1

opensuse advisories openSUSE-SU-2026:21761-1openSUSE-SU-2026:11047-1

Is CVE-2026-53622 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-53622 updated cvss 9.1

github.com/traefik/traefik: Traefik: mTLS enforcement bypass due to HTTP/3 TLS configuration flaw

  • Red Hat OpenShift Dev Spaces 3.30 devspaces/traefik-rhel9 1787756799
    fixed: vendor fix RHSA-2026:62260
  • Red Hat OpenShift Dev Spaces 3.30 devspaces/udi-rhel9 1787764814, devspaces/code-rhel9 1787762793, devspaces/server-rhel9 1787757597, devspaces/openvsx-rhel9 1787759145, devspaces/udi-base-rhel9 1787761882, devspaces/code-sshd-rhel9 1787762385, +10 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
4mo ago

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/traefik/traefik/security/advisories/GHSA-9cr8-q42q-g8m7 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 7.8 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
CISA ADP 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
GitHub 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
CNA 4.0 7.8 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:X/V:X/RE:X/U:X
NVD 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
go github.com/traefik/traefik/v3
>=3.7.0, <3.7.3
<3.6.18
<3.7.3
3.7.3
3.6.18
go github.com/traefik/traefik/v2
<2.11.51
2.11.51
go github.com/traefik/traefik
<=1.7.34
all versions
 no fix listed

Affected products

  • traefik traefik
  • Red Hat Red Hat OpenShift Dev Spaces 3.30

Classification

Weakness
  • CWE-288 Authentication Bypass Using an Alternate Path or Channel
  • CWE-289 Authentication Bypass by Alternate Name

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.