Junglewise Threat Intelligence

CVE-2026-31837: Istio JWKS resolver failure exposes hardcoded default keys

CVE-2026-31837 · Severity: high · CVSS 7.5 · Published 2026-03-10

Vendors: Red Hat.

Executive brief

Istio is an open-source platform used to manage and secure communication between microservices in cloud environments. A security flaw has been identified where the system may fail to properly validate security tokens if its internal resolver service becomes unavailable. This could allow an attacker to bypass intended security policies and access sensitive information by relying on hardcoded default settings that should not be exposed.

Technical details

A vulnerability exists in Istio's authentication mechanism where a failure in the JSON Web Key Set (JWKS) resolver leads to the exposure of hardcoded default keys. This occurs if the resolver becomes unavailable or a fetch operation fails, causing the system to fall back to these defaults regardless of the RequestAuthentication resource configuration. An unauthenticated remote attacker can exploit this behavior to bypass security controls and gain unauthorized access to sensitive information (CWE-200). The issue is rooted in improper handling of resolver failures and the use of default credentials (CWE-1392). Patches are available in versions 1.29.1, 1.28.5, and 1.27.8.

Affected products

  • Istio Istio < 1.27.8, >= 1.28.0-alpha.0, < 1.28.5, >= 1.29.0-alpha.0, < 1.29.1
  • Red Hat Red Hat OpenShift AI 2.25
  • Red Hat Red Hat OpenShift Service Mesh 3.0, 3.1, 3.2

Timeline

  • 2026-03-10: disclosed: Initial advisory published by Istio and GitHub
  • 2026-03-10: patched: Fixes released in versions 1.29.1, 1.28.5, and 1.27.8
  • 2026-04-23: advisory: Red Hat issued security advisory RHSA-2026:10184 for OpenShift AI

References

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