Traefik is an HTTP reverse proxy and load balancer. Prior to 3.7.3, there is 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 3.7.3.
CVE-2026-53622
This critical-severity CVE scores 10.0 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 85% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 10.0
- EG Score
- 10.0(medium)
- EPSS
- 15.0%
- KEV
- Not listed
Published
June 16, 2026
Last Modified
June 30, 2026
Advisory Details (5)
Auto-updated Jun 30, 20262491924 – (CVE-2026-53622) CVE-2026-53622 github.com/traefik/traefik: Traefik: mTLS enforcement bypass due to HTTP/3 TLS configuration flaw
https://bugzilla.redhat.com/show_bug.cgi?id=2491924HTTP/3 mTLS bypass via exact SNI TLSOptions lookup for wildcard and mixed-case hosts · Advisory · traefik/traefik · GitHub
https://github.com/traefik/traefik/security/advisories/GHSA-9cr8-q42q-g8m7v3.7.3
Patch available: traefik/traefik v3.7.3
https://github.com/traefik/traefik/releases/tag/v3.7.3Vendor Advisories for CVE-2026-53622(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(3 across 1 ecosystem)
Go(3)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| github.com/traefik/traefik | — | — | — |
| github.com/traefik/traefik/v2 | — | — | — |
| Traefik | — | 3.7.3 | — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 45× in last 7d / 80× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-07 03:01 UTCEG score recompute
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- 2026-07-06 16:27 UTCEPSS rescore
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- 2026-07-04 06:31 UTCEPSS rescore
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- 2026-07-04 01:54 UTCEG score recompute
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- 2026-07-03 07:16 UTCEG score recompute
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- 2026-07-01 15:07 UTCEPSS rescore
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- 2026-06-30 23:22 UTCEPSS rescore
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- 2026-06-29 17:59 UTCEG score recompute
- 2026-06-29 14:06 UTCEPSS rescore
- 2026-06-29 14:06 UTCEPSS rescore
- 2026-06-29 13:58 UTCEG score recompute
- 2026-06-29 09:58 UTCEG score recompute
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- 2026-06-29 01:53 UTCEG score recompute
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- 2026-06-28 14:07 UTCEPSS rescore
- 2026-06-28 13:53 UTCEG score recompute
- 2026-06-28 09:52 UTCEG score recompute
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- 2026-06-28 04:56 UTCEPSS rescore
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- 2026-06-28 01:37 UTCEG score recompute
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- 2026-06-27 05:33 UTCEG score recompute▲ 2.20
- 2026-06-27 03:08 UTCEPSS rescore
- 2026-06-26 17:41 UTCNVD updateCVSS v3 → 10 · severity → CRITICAL
- 2026-06-26 16:27 UTCEG score recompute
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- 2026-06-25 13:49 UTCEPSS rescore
- 2026-06-25 01:09 UTCEG score recompute
- 2026-06-24 14:05 UTCEPSS rescore
- 2026-06-24 12:03 UTCEG score recompute▲ 7.80
- 2026-06-24 12:01 UTCNVD updateCVSS v3 → 7.8 · CVSS v4 → 7.8
- 2026-06-16 21:06 UTCEG score recompute
Frequently asked(5)
What is CVE-2026-53622?
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