CVE-2026-53622 — Traefik HTTP/3 TLS configuration selection flaw bypasses router mTLS
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.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.6% (30-day exploitation probability)+7
- Technical severity (critical)+10
- Automatable exploitation (SSVC)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — github.com (NIST National Vulnerability Database)
- Documented patch — github.com (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Traefik Traefik).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes matching the vulnerability class (authentication), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.8 | CVSS 4.0 | High | — | — | security-advisories@github.com via NIST National Vulnerability Database |
| 7.8 | CVSS 4.0 | High | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
| 10.0 | CVSS 3.1 | Critical | 3.9 | 5.8 | nvd@nist.gov via NIST National Vulnerability Database |
| 9.1 | CVSS 3.1 | Critical | 3.9 | 5.2 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c via NIST National Vulnerability Database |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
CWE-288 · Authentication Bypass Using an Alternate Path or Channel
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.63%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Review authentication logs: logins without MFA, anomalous sessions and recently created accounts.
Analysis and videos
CVE-2026-53622: Traefik HTTP/3 TLS configuration selection flaw bypasses router mTLS
Traefik releases before 3.7.3, 3.6.18 and 2.11.51 can let unauthenticated clients bypass router-specific mTLS when HTTP/3 is enabled on an entrypoint. The TLS configuration lookup on SNI is exact and case-sensitive, so wildcard and case-variant hostnames fall back to a default configuration that may not require client certificates. The record rates the issue critical and classifies it as CWE-288; the sources consulted do not confirm exploitation in the wild.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · traefik/traefik
- SSVC assessment updated
- Record published
- Fix documented
- CVSS changed · 10.0
- Source status changed · → Modified
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
9 on the record
- github.com/traefik/traefik/security/advisories/GHSA-9cr8-q42q-g8m7
- github.com/traefik/traefik/releases/tag/v3.7.3
- access.redhat.com/security/cve/CVE-2026-53622
- community.traefik.io/t/new-security-update-for-traefik-2-11-2-11-48-3-6-3-6-19-and-3-7-3-7
- bugzilla.redhat.com/show_bug.cgi
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53622.json
- github.com/traefik/traefik/compare/v3.6.17...v3.6.18
- github.com/traefik/traefik/pull/13214
- access.redhat.com/errata/RHSA-2026:62260
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-88012 Allocation of Resources Without Limits or Throttling in Traefik Sep 10, 2026
- High CVE-2026-88009 HTTP Request Smuggling in Traefik Sep 10, 2026
- High CVE-2026-88011 Authentication Bypass by Spoofing in Traefik Sep 10, 2026
- Critical CVE-2026-88008 HTTP Request Smuggling in Traefik Sep 10, 2026
- Critical CVE-2026-88007 Improper Authentication in Traefik Sep 10, 2026
- High CVE-2026-88004 Traefik is an open source HTTP reverse proxy and load balancer. From 3.2.0 until 3.7.13… Sep 10, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-53622 is "Traefik HTTP/3 TLS configuration selection flaw bypasses router mTLS", rated Critical. It affects Traefik (Traefik); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 10.0 describes technical severity. EPSS 0.63% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
Comments
Moderated technical discussion. Read the community guidelines.
No comments yet.
Sign in or create an account to comment and suggest corrections.