CVE-2026-4789
Published: 30 March 2026
Summary
CVE-2026-4789 is a critical-severity SSRF (CWE-918) vulnerability in Kyverno Kyverno. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 6.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 AC-4 (Information Flow Enforcement) and SI-10 (Information Input Validation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Validates inputs to Kyverno's CEL HTTP functions to prevent SSRF by blocking malicious URLs or request parameters.
Enforces information flow policies that restrict Kyverno's outbound HTTP requests to only authorized internal and external destinations.
Monitors and controls Kyverno's network communications at boundaries to block or detect SSRF-induced requests to internal resources.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
SSRF in network-accessible app directly enables T1190 exploitation; facilitates internal proxy for bypassing restrictions and accessing internal resources via T1090.001.
NVD Description
Kyverno, versions 1.16.0 and later, are vulnerable to SSRF due to unrestricted CEL HTTP functions.
Deeper analysisAI
CVE-2026-4789 is a Server-Side Request Forgery (SSRF) vulnerability, classified under CWE-918, affecting Kyverno versions 1.16.0 and later due to unrestricted CEL HTTP functions. Published on 2026-03-30, it carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating critical severity with network accessibility, low attack complexity, no privileges or user interaction required, and high impacts on confidentiality, integrity, and availability.
Unauthenticated remote attackers can exploit this vulnerability over the network. By leveraging the unrestricted CEL HTTP functions, they can induce Kyverno to make unintended requests, potentially accessing internal resources, bypassing network restrictions, or interacting with external services in ways that lead to significant compromise.
Advisories and further details are available in referenced sources, including the Kyverno GitHub repository at https://github.com/kyverno/kyverno, CERT KB entry at https://kb.cert.org/vuls/id/655822, and general SSRF guidance at https://portswigger.net/web-security/ssrf.
Details
- CWE(s)