Summary
Traefik: HTTP/3 mTLS bypass via exact SNI TLSOptions lookup for wildcard and mixed-case hosts
Impact
Deployments that use router TLSOptions as an access-control boundary for HTTP/3 can expose protected backends without client authentication.
The highest-impact case is mTLS:
- normal HTTP/2/TCP access to the protected host requires a client certificate
- HTTP/3 access to the same route falls back to the default TLS config
- the request is then routed to the protected backend without satisfying the route's mTLS policy
This can expose confidential data or privileged backend operations to unauthenticated network clients. The issue is especially severe because it does not require credentials, user interaction, or a prior foothold.
Possible workarounds until a fix is available:
- Disable HTTP/3 on entrypoints that rely on router-specific mTLS.
- Enforce mTLS in the default TLS options as well, so fallback TLS configuration is not weaker than router-specific configuration.
- Block UDP access to the HTTP/3 entrypoint.
- Enforce client authentication at an additional layer behind Traefik.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Frequently Asked Questions
- What is CVE-2026-53622? CVE-2026-53622 is a high-severity security vulnerability in Traefik (go), affecting versions <= 3.7.2. It is fixed in 3.7.3.
- Which packages are affected by CVE-2026-53622?
Traefik(go) (versions <= 3.7.2)github.com/traefik/traefik/v2(go) (versions <= 2.11.50)github.com/traefik/traefik(go) (versions <= 1.7.34)
- Is there a fix for CVE-2026-53622? Yes. CVE-2026-53622 is fixed in 3.7.3. Upgrade to this version or later.
- Is CVE-2026-53622 exploitable, and should I be worried? Whether CVE-2026-53622 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-53622 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-53622? Upgrade
Traefikto 3.7.3 or later.