Skip the router TLS configuration when the host header is an FQDNGHSA-hrhx-6h34-j5hc
HIGHFix: traefik/traefik#8764GHSA-hrhx-6h34-j5hc is a high-severity (CVSS 7.4) CWE-295 vulnerability in github.com/traefik/traefik/v2. A fix is available for github.com/traefik/traefik/v2 — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-hrhx-6h34-j5hc.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-hrhx-6h34-j5hc by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
github.com/traefik/traefik/v2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Impact
People that configure mTLS between Traefik and clients.
For a request, the TLS configuration choice can be different than the router choice, which implies the use of a wrong TLS configuration.
-
When sending a request using FQDN handled by a router configured with a dedicated TLS configuration, the TLS configuration falls back to the default configuration that might not correspond to the configured one.
-
If the CNAME flattening is enabled, the selected TLS configuration is the SNI one and the routing uses the CNAME value, so this can skip the expected TLS configuration.
Patches
Traefik v2.6.x: https://github.com/traefik/traefik/releases/tag/v2.6.1
Workarounds
Add the FDQN to the host rule:
Example:
whoami:
image: traefik/whoami:v1.7.1
labels:
traefik.http.routers.whoami.rule: Host(`whoami.example.com`, `whoami.example.com.`)
traefik.http.routers.whoami.tls: true
traefik.http.routers.whoami.tls.options: mtls@file
There is no workaround if the CNAME flattening is enabled.
For more information
If you have any questions or comments about this advisory, please open an issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/traefik/traefik/v2 | all versions | 2.6.1go get github.com/traefik/traefik/v2@v2.6.1 |
Affected Products
communications unified inventory managementoracletraefiktraefikDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/traefik/traefik/v2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/traefik/traefik/v2 to 2.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hrhx-6h34-j5hc is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is GHSA-hrhx-6h34-j5hc in your dependencies?
Find it across Go, including transitive dependencies.