Which versions of Calico are affected by CVE-2026-6540?

A flaw in Tigera Calico's network policy enforcement allows attackers on the network to bypass configured access restrictions through request manipulation, potentially enabling lateral movement…. A patch is available.

How to fix or mitigate CVE-2026-6540?

Within 24 hours, determine whether Application Layer Policy is enabled in your Calico, Calico Enterprise, or Calico Cloud deployments; prioritize environments with ALP enabled for remediation. Within 7 days, apply the vendor-released patch referenced in Tigera advisory TTA-2026-005 to all affected instances. Within 30 days, confirm patch deployment across all production environments and validate that Application Layer Policy authorization enforcement is functioning as intended.

Calico CVE-2026-6540

Q: What is the CVSS score of CVE-2026-6540?

CVE-2026-6540 has a CVSS 4.0 base score of 7.9 (High). CVSS 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.4%.

EUVD-2026-51153 HIGH

Path Traversal (CWE-22)

2026-07-30 Tigera

GHSA-gm75-wg2c-p77x

Path Traversal Calico Calico Enterprise Calico Cloud

7.9

CVSS 4.0 · Vendor: Tigera

Severity by source

Vendor (Tigera) PRIMARY

7.9 HIGH

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

10.0 CRITICAL

Network-reachable with no RBAC (AV:N/PR:N); the enforcer authorizes but a different downstream component is impacted, so S:C with high confidentiality/integrity and low availability on the restricted endpoint.

3.1 AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:L

Primary rating from Vendor (Tigera).

CVSS VectorVendor: Tigera

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Source Code Evidence Fetched

Jul 30, 2026 - 15:21 vuln.today

Analysis Generated

Jul 30, 2026 - 15:21 vuln.today

CVE Published

Jul 30, 2026 - 14:45 cve.org

HIGH 7.9

DescriptionCVE.org

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.

AnalysisAI

Authorization bypass in Tigera Calico, Calico Enterprise, and Calico Cloud allows network-adjacent attackers with no special RBAC to reach HTTP endpoints that Application Layer Policy was configured to restrict. Because Dikastes matched raw request paths without RFC 3986/7230 normalization, requests using path-traversal segments, percent-encoded or backslash separators, repeated slashes, or matrix parameters were authorized under a permitted Prefix rule while the downstream workload or fronting proxy normalized them to the restricted endpoint. A vendor fix exists (PRs 12531/12532/12533, advisory TTA-2026-005); no public exploit identified at time of analysis, and the affected Application Layer Policy feature is disabled by default.

Technical ContextAI

The flaw lives in Calico's Application Layer Policy (ALP), an optional Layer-7 enforcement plane implemented by the Dikastes sidecar/authorization service, which evaluates HTTP method and path rules for workload-to-workload traffic in a Kubernetes mesh. The root cause is CWE-22 (Improper Limitation of a Pathname to a Restricted Directory / path traversal): matchHTTPPaths in app-policy/checker/match.go compared the request-target using strings.HasPrefix against raw bytes after stripping only the query and fragment. It never percent-decoded, never collapsed repeated slashes, never resolved '.'/'..' segments, and never handled backslashes or per-segment matrix parameters. The fix introduces normalizeHTTPPath, which decodes once, rejects surviving %2e/%2f/%5c double-encoding and NUL bytes, folds backslashes, strips matrix params (JSR-339/Servlet-style ';...'), and applies path.Clean, plus segmentPrefixMatch to anchor prefix matches to segment boundaries - aligning the authorization view with how Tomcat, Jetty, Spring, nginx, and IIS actually dispatch paths.

RemediationAI

Patch available per vendor advisory TTA-2026-005 (https://www.tigera.io/security-bulletins/tta-2026-005/); the upstream fix is available via projectcalico/calico PRs 12531, 12532, and 12533, so upgrade Calico, Calico Enterprise, or Calico Cloud to the fixed release named in that bulletin (exact patched version not present in the provided data - confirm from the advisory before scheduling). If you cannot upgrade immediately, the strongest compensating control is to disable Application Layer Policy / Dikastes HTTP path enforcement if it is not essential, since it is off by default anyway; where ALP is required, avoid relying on Prefix path rules for security-critical segmentation and instead enforce restricted endpoints at the workload or fronting proxy with its own normalized path checks, and configure that proxy to reject ambiguous paths (encoded slashes, backslashes, '..', repeated slashes, matrix parameters) - accepting the trade-off that stricter proxy normalization may break clients that legitimately send encoded paths.