CVE-2026-39350

Istio AuthorizationPolicy Incorrect Regex Matching of Dots in serviceAccounts Fields Allows Policy Bypass

MEDIUM
5.4
CVSS Score
Published: April 15, 2026 at 10:42 PM UTC
Updated: June 17, 2026 at 10:41 AM UTC
1 product affected across 1 vendorIstio

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Severity
MEDIUM5.4
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.27.9v < 1.28.6v < 1.29.21.25.0 ≤ v < 1.27.91.28.0 ≤ v < 1.28.61.29.0 ≤ v < 1.29.2
Affected range stops below 1.27.9, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.28.6, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.29.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (1)

x_refsource_CONFIRMVendor Advisory
Source: cverecord
https://github.com/istio/istio/security/advisories/GHSA-9gcg-w975-3rjh

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.4MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-185CWE-863

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