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.valueThe 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:
Other use cases of Lua filter are not vulnerable.
The fix is available in Contour v1.33.4, v1.32.5, and v1.31.6.
text/template is removed. Requires Envoy 1.35.0 or later.There are no workarounds. Users should upgrade to a patched version.
1.31.61.32.51.33.4Exploitability
AV:NAC:LPR:LUI:NScope
S:UImpact
C:HI:NA:H8.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H