CVE-2026-26055

Unauthenticated Admission Webhook Endpoints in Yoke ATC

Vulnerability Type: Missing Authentication / Authentication Bypass

Attack Prerequisites:

• Attacker has access to a pod within the cluster network
• Network policies do not restrict access to the ATC service (common in default configurations)

Impact Assessment:

• Confidentiality: Medium - Attacker can trigger WASM execution which may access controller context data
• Integrity: High - Combined with VUL-001, attacker can create arbitrary Kubernetes resources
• Availability: Medium - Attacker can cause resource exhaustion through repeated requests

Attack Scenario:

1. Attacker compromises a pod or gains access to the cluster network
2. Attacker sends crafted AdmissionReview requests directly to ATC webhook
3. ATC processes requests without verifying they came from the API Server
4. Combined with annotation injection (VUL-001), attacker can execute arbitrary WASM code
5. Malicious WASM can create resources or exfiltrate data using ATC's cluster-admin privileges

A critical operation is accessible without requiring any authentication. Typical impact: any user can invoke the privileged function.

CVE-2026-26055 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.

Kodem intelligence

1. What is CVE-2026-26055? CVE-2026-26055 is a high-severity missing authentication for critical function vulnerability in github.com/yokecd/yoke (go), affecting versions <= 0.19.0. No fixed version is listed yet. A critical operation is accessible without requiring any authentication.
2. How severe is CVE-2026-26055? CVE-2026-26055 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/yokecd/yoke are affected by CVE-2026-26055? github.com/yokecd/yoke (go) versions <= 0.19.0 is affected.
4. Is there a fix for CVE-2026-26055? No fixed version is listed for CVE-2026-26055 yet. Monitor the advisory for updates and apply mitigations in the interim.
5. Is CVE-2026-26055 exploitable, and should I be worried? Whether CVE-2026-26055 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-26055 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-26055? No fixed version is listed yet. In the interim: Keep the dependency up to date. Add authentication gating to all sensitive endpoints.