Istio up to 1.27.8/1.28.5/1.29.1 notServiceAccounts incorrect regex

Summaryinfo

A vulnerability marked as critical has been reported in Istio up to 1.27.8/1.28.5/1.29.1. This affects an unknown part. This manipulation of the argument notServiceAccounts causes incorrect regex. This vulnerability is registered as CVE-2026-39350. Remote exploitation of the attack is possible. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Istio up to 1.27.8/1.28.5/1.29.1. It has been declared as critical. Affected by this vulnerability is an unknown code. The manipulation of the argument notServiceAccounts with an unknown input leads to a incorrect regex vulnerability. The CWE definition for the vulnerability is CWE-185. The product specifies a regular expression in a way that causes data to be improperly matched or compared. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Istio is an open platform to connect, manage, and secure microservices. In versions 1.25.0 through 1.27.8, 1.28.0 through 1.28.5, 1.29.0, and 1.29.1, the serviceAccounts and notServiceAccounts fields in AuthorizationPolicy incorrectly interpret dots (.) as a regular expression matcher. Because . is a valid character in a service account name, an AuthorizationPolicy ALLOW rule targeting a service account such as cert-manager.io also matches cert-manager-io, cert-managerXio, etc. A DENY rule targeting the same name fails to block those variants. Fixes are available in versions 1.29.2, 1.28.6, and 1.27.9.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-39350 since 04/06/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details are known, but no exploit is available.

Upgrading to version 1.27.9, 1.28.6 or 1.29.2 eliminates this vulnerability.

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Productinfo

Name

• Istio

Version

• 1.27.0
• 1.27.1
• 1.27.2
• 1.27.3
• 1.27.4
• 1.27.5
• 1.27.6
• 1.27.7
• 1.27.8
• 1.28.0
• 1.28.1
• 1.28.2
• 1.28.3
• 1.28.4
• 1.28.5
• 1.29.0
• 1.29.1

Website

• Product: https://github.com/istio/istio/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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