GHSA-g3xr-5w5j-w4q4
Contour has Improper JWT Verification for Non-SNI Requests on Virtual Hosts with Fallback Certificate Enabled
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| Go | github.com/projectcontour/contour | >= 1.23.0, < 1.33.5 | 1.33.5 |
Details
As written in the advisory (Markdown source, shown as plain text).
### Impact
When an `HTTPProxy` is configured with incompatible combination of both `.spec.virtualhost.tls.enableFallbackCertificate: true` and `.spec.virtualhost.jwtProviders`, Contour does not reject the configuration. Consequently, requests from clients that do not send TLS SNI or send an unrecognized SNI (one that does not match any `HTTPProxy` FQDN) bypass configured JWT verification and are proxied to upstream services without a valid token.
To list all `HTTPProxies` with this invalid configuration, run
```bash
kubectl get httpproxies -A -o json | jq -r '
.items[]
| select(.spec.virtualhost | .tls.enableFallbackCertificate and .jwtProviders)
| "Invalid HTTPProxy found: \(.metadata.namespace)/\(.metadata.name)"
'
```
### Patches
This issue is fixed in Contour v1.33.5. Contour now rejects and marks invalid any `HTTPProxy` resources that combine `.spec.virtualhost.tls.enableFallbackCertificate: true` with `.spec.virtualhost.jwtProviders`. Affected resources will receive a status condition with the error reason `TLSIncompatibleFeatures`.
### Workarounds
Do not enable `.spec.virtualhost.tls.enableFallbackCertificate` on `HTTPProxy` resources that also define `.spec.virtualhost.jwtProviders`. Remove one of the two settings to avoid the invalid configuration.
### References
- Contour fallback certificate documentation: https://projectcontour.io/docs/main/config/tls-termination/#fallback-certificate
- Contour JWT verification documentation: https://projectcontour.io/docs/main/config/jwt-verification/
References
External links from the advisory. They lead to third-party sites.