GHSA-x4mj-7f9g-29h4 — contour
HIGHGHSA-x4mj-7f9g-29h4 is a high-severity (CVSS 8.1) Code Injection vulnerability in github.com/projectcontour/contour. A fix is available for github.com/projectcontour/contour — see the affected versions and patch details below.
Contour has Lua code injection via Cookie Path Rewrite Policy
Exploitation Status
No confirmed exploitation observed yet
- 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-x4mj-7f9g-29h4.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-x4mj-7f9g-29h4 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/projectcontour/contour🐹github.com/projectcontour/contour🐹github.com/projectcontour/contourReal-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
Contour's Cookie Rewriting feature is vulnerable to Lua code injection. An attacker with RBAC permissions to create or modify HTTPProxy resources can craft a malicious value in the following fields that results in arbitrary code execution in the Envoy proxy:
spec.routes[].cookieRewritePolicies[].pathRewrite.valuespec.routes[].services[].cookieRewritePolicies[].pathRewrite.value
The cookie rewriting feature is internally implemented using Envoy's HTTP Lua filter. User-controlled values are interpolated into Lua source code using Go text/template without sufficient sanitization.
The injected code only executes when processing traffic on the attacker's own route, which they already control. However, since Envoy runs as shared infrastructure, the injected code can also:
- Read Envoy's xDS client credentials from the filesystem, which could be used to read all Contour xDS configuration, including TLS certificates and private keys of other tenants.
- Cause denial of service for other tenants sharing the Envoy instance.
Other use cases of Lua filter are not vulnerable.
Patches
The fix is available in Contour v1.33.4, v1.32.5, and v1.31.6.
- v1.33.4: User-provided values are no longer interpolated into Lua code. Use of
text/templateis removed. Requires Envoy 1.35.0 or later. - v1.32.5, v1.31.6: User-provided values are escaped before interpolation into Lua code.
Workarounds
There are no workarounds. Users should upgrade to a patched version.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/projectcontour/contour | ≥ 1.19.0&&< 1.31.6 | 1.31.6go get github.com/projectcontour/contour@v1.31.6 |
| 🐹Go | github.com/projectcontour/contour | ≥ 1.32.0&&< 1.32.5 | 1.32.5go get github.com/projectcontour/contour@v1.32.5 |
| 🐹Go | github.com/projectcontour/contour | ≥ 1.33.0&&< 1.33.4 | 1.33.4go get github.com/projectcontour/contour@v1.33.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/projectcontour/contour, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/projectcontour/contour to 1.31.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x4mj-7f9g-29h4 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-x4mj-7f9g-29h4 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-x4mj-7f9g-29h4. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-x4mj-7f9g-29h4 in your dependencies?
O3 Security finds GHSA-x4mj-7f9g-29h4 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.