# CVE-2026-53622: Traefik mTLS bypass in HTTP/3 via exact SNI lookup failure

Source: https://junglewise.ai/threats/cve-2026-53622-traefik-mtls-bypass-in-http-3-via-exact-sni-lookup-failure  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-23. Updated: 2026-06-23  
License: CC BY 4.0 with a link back

CVE-2026-53622 · Severity: high · CVSS 3.1 · Published 2026-06-23

Traefik is a popular open-source tool used to route and balance web traffic to different applications. A security flaw in its handling of modern HTTP/3 (QUIC) connections allows attackers to bypass security rules that require a digital certificate for access. This means an unauthorized user could potentially access private internal services that were supposed to be protected by mutual TLS (mTLS) authentication.

Technologies: [github.com/traefik/traefik (Go)](https://junglewise.ai/threats/technologies/github-com-traefik-traefik), [github.com/traefik/traefik/v2 (Go)](https://junglewise.ai/threats/technologies/github-com-traefik-traefik-v2), [github.com/traefik/traefik/v3 (Go)](https://junglewise.ai/threats/technologies/github-com-traefik-traefik-v3), [Traefik Labs Traefik Proxy](https://junglewise.ai/threats/technologies/traefik-proxy). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Traefik Labs](https://junglewise.ai/threats/vendors/traefik-labs).

## Quick answers

**Is CVE-2026-53622 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-53622 being exploited in the wild.

**How severe is CVE-2026-53622?** High severity, with a CVSS score of 3.1, published 23 June 2026.

**Which products and versions are affected?** github.com/traefik/traefik (Go) <= 1.7.34, SEMVER:introduced=0, SEMVER:introduced=0,last_affected=1.7.34; github.com/traefik/traefik/v2 (Go) <= 2.11.50, SEMVER:introduced=0,fixed=2.11.51; github.com/traefik/traefik/v3 (Go) SEMVER:introduced=0,fixed=3.7.3, SEMVER:introduced=3.7.0,fixed=3.7.3; Traefik Labs Traefik Proxy < 3.7.3.

**Is there a fix for CVE-2026-53622?** Yes. github.com/traefik/traefik/v2 (Go): upgrade to 2.11.51 or later; github.com/traefik/traefik/v3 (Go): upgrade to 3.7.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-53622 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-53622?** Check whether you run github.com/traefik/traefik (Go), github.com/traefik/traefik/v2 (Go), github.com/traefik/traefik/v3 (Go) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/traefik/traefik/v2 (Go): upgrade to 2.11.51 or later

  ```sh
  go get github.com/traefik/traefik/v2@v2.11.51
  ```

- github.com/traefik/traefik/v3 (Go): upgrade to 3.7.3 or later

  ```sh
  go get github.com/traefik/traefik/v3@v3.7.3
  ```


## Technical details

A vulnerability exists in Traefik's HTTP/3 (QUIC) TLS configuration selection logic. When HTTP/3 is enabled, the TLS handshake performs an exact, case-sensitive map lookup on the SNI value to select the appropriate TLS configuration. This lookup fails for wildcard host patterns (e.g., *.example.com) or mixed-case variants of a hostname. In these cases, Traefik falls back to the default TLS configuration. If the default configuration does not require client certificates, an unauthenticated attacker can complete the handshake and reach backends that were intended to be protected by router-specific mTLS policies. This issue is resolved in version 3.7.3.

## Affected products

- Traefik Traefik < 3.7.3

## Identifiers

- CVE-2026-53622
- GHSA-9cr8-q42q-g8m7
- GO-2026-5287

## Timeline

- 2026-06-04: patched: Version 3.7.3 released
- 2026-06-05: advisory: GitHub Security Advisory GHSA-9cr8-q42q-g8m7 published
- 2026-06-23: disclosed: CVE-2026-53622 published to NVD

## References

- [https://github.com/traefik/traefik/releases/tag/v3.7.3](https://github.com/traefik/traefik/releases/tag/v3.7.3)
- [https://github.com/traefik/traefik/security/advisories/GHSA-9cr8-q42q-g8m7](https://github.com/traefik/traefik/security/advisories/GHSA-9cr8-q42q-g8m7)

## Related threats

- [Traefik BasicAuth singleflight username enumeration via timing oracle](https://junglewise.ai/threats/cve-2026-88010-traefik-basicauth-singleflight-username-enumeration-via-timing)
- [Traefik readTimeout not enforced on HTTP/3 connections](https://junglewise.ai/threats/cve-2026-88012-traefik-readtimeout-not-enforced-on-http-3-connections)
- [Traefik ForwardAuth identity spoofing via header alias](https://junglewise.ai/threats/cve-2026-88011-traefik-forwardauth-identity-spoofing-via-header-alias)
- [Traefik rootless HTTP/1 request-target routing bypass](https://junglewise.ai/threats/cve-2026-88009-traefik-rootless-http-1-request-target-routing-bypass)
- [Traefik HTTP request smuggling via unrestricted protocol upgrade](https://junglewise.ai/threats/cve-2026-88008-traefik-http-request-smuggling-via-unrestricted-protocol-upgrade)