CVE-2026-31837

Modified Modified - Updated After Analysis

JWKS Resolver Failure in Istio Exposes Hardcoded Credentials

Publication date: 2026-03-10

Last updated on: 2026-06-30

Assigner: GitHub, Inc.

Description

Istio is an open platform to connect, manage, and secure microservices. Prior to 1.29.1, 1.28.5, and 1.27.8, a user of Istio is impacted if the JWKS resolver becomes unavailable or the fetch fails, exposing hardcoded defaults regardless of use of the RequestAuthentication resource. This vulnerability is fixed in 1.29.1, 1.28.5, and 1.27.8.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-03-10

Last Modified

2026-06-30

Generated

2026-07-06

AI Q&A

2026-03-11

EPSS Evaluated

2026-07-05

NVD

CVE-2026-31837

EUVD

EUVD-2026-10938

Affected Vendors & Products

Vendor	Product	Version / Range
istio	istio	to 1.27.8 (exc)
istio	istio	From 1.28.0 (inc) to 1.28.5 (exc)
istio	istio	From 1.29.0 (inc) to 1.29.1 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-1392	The product uses default credentials (such as passwords or cryptographic keys) for potentially critical functionality.
CWE-200	The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

Attack-Flow Graph

Executive Summary

This vulnerability affects Istio, an open platform used to connect, manage, and secure microservices. Before versions 1.29.1, 1.28.5, and 1.27.8, if the JWKS (JSON Web Key Set) resolver became unavailable or if fetching the keys failed, Istio would expose hardcoded default keys. This exposure happens regardless of whether the RequestAuthentication resource is used, potentially allowing unauthorized access or bypassing authentication mechanisms.

Impact Analysis

The impact of this vulnerability is that an attacker could exploit the failure of the JWKS resolver to cause Istio to use hardcoded default keys. This could lead to unauthorized access to microservices or bypassing of authentication controls, compromising the security of applications relying on Istio for service-to-service authentication.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, upgrade Istio to version 1.29.1, 1.28.5, or 1.27.8 or later, as these versions contain the fix for the issue where the JWKS resolver becomes unavailable or fetch fails, exposing hardcoded defaults.

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