Executive brief
Tigera Calico is a networking and security solution for containers and Kubernetes. A vulnerability in its Application Layer Policy component could allow an attacker to bypass security rules intended to restrict access to specific web addresses. By using specially crafted web requests (such as those containing extra slashes or encoded characters), an attacker can trick the security checker into allowing access to restricted data or administrative endpoints.
Technical details
A path traversal and normalization vulnerability exists in Calico's Dikastes component when evaluating Application Layer Policy (ALP) rules. The 'matchHTTPPaths' function performs a byte-for-byte comparison of the raw request-target against policy rules without prior normalization. An attacker can use path-traversal segments (../), percent-encoded slashes, or repeated slashes to bypass prefix-based restrictions. While Dikastes may authorize the unnormalized path under a permissive rule, the downstream workload or proxy typically normalizes the path, leading to the exposure of restricted endpoints. The fix introduces RFC 3986/7230 normalization, including percent-decoding and dot-segment resolution, before policy evaluation.
Affected products
- Tigera Calico < 3.31.6
- Tigera Calico Enterprise < 3.21.7, 3.22.0 to < 3.22.4
- Tigera Calico Cloud < 22.4.0
Timeline
- 2026-04-17: patched: Initial fix submitted to master branch
- 2026-07-30: disclosed: CVE-2026-6540 published