Summary
Contour has Improper JWT Verification for Non-SNI Requests on Virtual Hosts with Fallback Certificate Enabled
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/
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
kubectl get httpproxies -A -o json | jq -r '
.items[]
| select(.spec.virtualhost | .tls.enableFallbackCertificate and .jwtProviders)
| "Invalid HTTPProxy found: \(.metadata.namespace)/\(.metadata.name)"
'
CVE-2026-50149 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.33.5); upgrading removes the vulnerable code path.
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.
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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.
Frequently Asked Questions
- What is CVE-2026-50149? CVE-2026-50149 is a medium-severity security vulnerability in github.com/projectcontour/contour (go), affecting versions >= 1.23.0, < 1.33.5. It is fixed in 1.33.5.
- How severe is CVE-2026-50149? CVE-2026-50149 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/projectcontour/contour are affected by CVE-2026-50149? github.com/projectcontour/contour (go) versions >= 1.23.0, < 1.33.5 is affected.
- Is there a fix for CVE-2026-50149? Yes. CVE-2026-50149 is fixed in 1.33.5. Upgrade to this version or later.
- Is CVE-2026-50149 exploitable, and should I be worried? Whether CVE-2026-50149 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-2026-50149 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-2026-50149? Upgrade
github.com/projectcontour/contourto 1.33.5 or later.