CVE-2026-54523: Kyverno's NamespacedGeneratingPolicy generator.apply() namespace argument unvalidated -- background controller creates RoleBindings in any namespace including kube-system

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.5%, percentile 39: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 39% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). Exposure depends on who can log in.
• Only applies if your dependency tree includes github.com/kyverno/kyverno (Go) >= 1.18.0, <= 1.18.1, fixed in 1.18.2. Check your lockfile, including transitive dependencies.

What it is

Kyverno is a policy engine designed for cloud native platform engineering teams. From 1.18.0 until 1.18.2, the NamespacedMutatingPolicy CEL compiler exposes the generator library to matchConditions, allowing a namespace-scoped policy to invoke generator.apply(namespace, resources) with an arbitrary target namespace. The validation in pkg/cel/policies/mpol/validate.go checks that the policy compiles but does not enforce namespace scope, and GenerateResources in pkg/cel/libs/context.go does not reject the cross-namespace target. A user who can create NamespacedMutatingPolicy objects in one namespace can cause the admission controller, operating with cluster-wide privileges, to create ConfigMaps, NetworkPolicies, Secrets, RoleBindings, and other resources in another namespace, enabling unauthorized modification and potential privilege escalation. This issue is fixed in version 1.18.2.

From the GitHub advisory

Summary

In Kyverno v1.18.1, a tenant who can create a NamespacedMutatingPolicy in their own namespace can instruct the admission controller to generate resources in any namespace by passing an arbitrary namespace string to the CEL generator.apply(namespace, resources) function.

Details

pkg/cel/libs/context.go:177 declares GenerateResources(namespace string, dataList []map[string]any). The namespace argument arrives unvalidated from the CEL expression generator.apply(" ", [...]).

Version-Specific Impact

Weakness type: CWE-862.

Product: github.com/kyverno/kyverno (Go) · Assigned by: GitHub_M · Published: 2026-08-26

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.47% probability of exploitation activity in the next 30 days; percentile 39.

Timeline

• 2026-08-26 — CVE record last updated
• 2026-08-26 — CVE record published by GitHub_M
• 2026-08-26 — GitHub-reviewed advisory GHSA-79gf-7frw-68m9 published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-79gf-7frw-68m9 github.com
2. CVE.org record CVE-2026-54523 cve.org
3. NVD entry CVE-2026-54523 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. github.com github.com
6. github.com github.com

Critical Go advisories · Today’s Security Digest