CVE-2026-6540
Undergoing Analysis Undergoing Analysis - In Progress

Calico Application Layer Policy Path Normalization Bypass

Vulnerability report for CVE-2026-6540, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-07-30

Last updated on: 2026-07-30

Assigner: Tigera, Inc.

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.

CVSS Scores

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Meta Information

Published
2026-07-30
Last Modified
2026-07-30
Generated
2026-07-31
AI Q&A
2026-07-31
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
tigera calico *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-23 The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as ".." that can resolve to a location that is outside of that directory.
CWE-22 The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Attack-Flow Graph

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Executive Summary

Calico's Application Layer Policy feature, which is not enabled by default, has a flaw in its HTTP rule enforcement. When enforcing path-based rules, it fails to properly normalize URLs. This means attackers can bypass restrictions by using path-traversal segments, encoded slashes, or repeated slashes in HTTP requests. The policy may allow a request while the actual server normalizes the path and serves a restricted endpoint.

Impact Analysis

An attacker with network access but no special permissions could exploit this to access HTTP endpoints that were supposed to be restricted by Calico's policies. This could lead to unauthorized access to sensitive data or services within your network.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, which may violate compliance requirements under GDPR, HIPAA, or other regulations. Unauthorized access to restricted endpoints could result in data breaches, triggering legal and financial penalties.

Mitigation Strategies

Enable Application Layer Policy in Calico and ensure URL path normalization is enforced. Review and update HTTP path rules to account for path-traversal segments, encoded slashes, and repeated slashes. Test policies to confirm restricted endpoints are properly blocked.

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