Kyverno SSRF via Variable Substitution in API Calls

Kyverno before 1.18.0 contains a server-side request forgery vulnerability in apiCall.service.url that allows authenticated users to send arbitrary HTTP requests by injecting user-controlled input through variable substitution. Attackers can target internal services, cloud metadata endpoints, and loopback addresses, with response data reflected in admission error messages enabling non-blind data exfiltration.

Casky was already ahead

This CVE exploits attack patterns that Casky's 331matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

Kyverno before version 1.18.0 contains a server-side request forgery (SSRF) vulnerability in its apiCall.service.url function that allows authenticated users to inject malicious input through variable substitution mechanisms. This vulnerability is particularly dangerous because it enables attackers to send arbitrary HTTP requests to internal services, cloud metadata endpoints (such as AWS IMDSv1), and loopback addresses. The reflected response data in admission error messages facilitates non-blind data exfiltration, meaning attackers can directly observe sensitive information without blind exploitation techniques. Organizations running vulnerable Kyverno instances in Kubernetes environments face significant risk, as policy engine compromises can lead to cluster-wide lateral movement, credential theft, and unauthorized access to cloud provider metadata containing authentication tokens.

Casky's 331 matching security skills leverage Claude AI with extended reasoning to detect the attack patterns behind this CVE by mapping observations to MITRE ATT&CK techniques TA0001 (Reconnaissance) and TA0006 (Credential Access). Practitioners using Casky would identify suspicious patterns including: anomalous HTTP requests originating from Kyverno components targeting internal IP ranges or cloud metadata services (169.254.169.254, 127.0.0.1), variable substitution payloads in policy definitions or webhook configurations, and error messages containing unexpected external service responses or sensitive data leakage. The platform's extended reasoning capabilities correlate CWE-918 SSRF indicators with authentication context and policy execution flows, helping security teams distinguish between legitimate Kyverno operations and exploitation attempts, then map findings to appropriate remediation actions such as upgrading to version 1.18.0 and implementing network segmentation policies.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

331 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-84196.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

Run

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

MITRE ATT&CK Techniques

TA0001 TA0006

Investigate the attack patterns behind CVE-2026-84196

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