{"id":"CVE-2026-124440","published":"2026-11-08T14:18:10.633","lastModified":"2026-11-09T15:17:15.840","description":"Kyverno from 1.19.1 before 1.19.2 contains an authorization bypass vulnerability in the apiCall namespace clamp that allows namespace tenants to issue cross-namespace and cluster-scoped API requests by appending malformed percent-escapes to urlPath. Attackers can create namespaced Policies whose apiCall runs as the admission-controller ServiceAccount to read other namespaces' resources and create mutating webhooks, escalating to cluster admin.","cvssScore":9.9,"cvssSeverity":"CRITICAL","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","cwes":["CWE-441"],"vendors":[],"products":[],"references":[{"url":"https://github.com/kyverno/kyverno/security/advisories/GHSA-39w8-hv5g-f73w","tags":[]},{"url":"https://www.vulncheck.com/advisories/kyverno-1.19.1-privilege-escalation-via-apicall-namespace-clamp-bypass","tags":[]}],"exploitRefs":[{"url":"https://github.com/kyverno/kyverno/security/advisories/GHSA-39w8-hv5g-f73w","tags":[]}],"hasPoc":true,"ai":{"summary":"Kyverno versions 1.19.1 and earlier contain an authorization bypass in the apiCall namespace clamp due to improper handling of percent-encoded characters in urlPath, allowing low-privilege users to issue cluster-scoped API requests as the admission-controller ServiceAccount. This enables cross-namespace resource reads and creation of mutating webhooks, leading to potential privilege escalation to cluster admin.","exploitability":"Exploitation requires authenticated access with permission to create namespaced Policies (PR:L) and involves crafting maliciously encoded urlPath values; public exploits exist, indicating low-to-moderate technical barrier for attackers with existing Kyverno access.","blast_radius":"Successful exploitation allows full cluster compromise via unauthorized webhook creation and cross-namespace data exfiltration, affecting all tenants in multi-tenant clusters using Kyverno admission control.","remediation":"Upgrade to Kyverno 1.19.2 or later, which patches the urlPath percent-escape handling flaw in the apiCall namespace clamp.","detection":"Defenders should monitor for Policy resources with urlPath fields containing unusual percent-encoding patterns (e.g., %2f, %2F, %252f) that resolve to cluster-scoped endpoints or non-local namespaces when evaluated by the admission controller; also alert on unexpected use of cluster-scoped resources by the kyverno-admission-controller ServiceAccount in audit logs.","tags":["auth-bypass","privilege-escalation","kyverno","webhook-abuse","multi-tenant-risk"],"model":"garnet-coder","analyzedAt":"2026-11-09T09:41:49.819Z"}}