Istio: AuthorizationPolicy serviceAccounts regex injection via unescaped dots (CVE-2026-39350) | HOL Guard CVE

Medium · CVSS 5.4CVE-2026-39350GHSA-9GCG-W975-3RJH

Istio: AuthorizationPolicy serviceAccounts regex injection via unescaped dots

Answer in brief

CVE-2026-39350 records a Medium severity (CVSS 5.4) vulnerability in Istio: AuthorizationPolicy serviceAccounts regex injection via unescaped dots. The current sources do not mark it as known exploited. The current feed maps istio.io/istio (go). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Apr 16, 2026Updated Sep 10, 2026Source checked Sep 10, 2026First seen by HOL Sep 10, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.4
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 5.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps istio.io/istio (go). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
istio.io/istiogo	>=0.0.0-20241024090207-0bf27d49ba4b <0.0.0-20260403004500-692e460c342d	0.0.0-20260403004500-692e460c342d

Recommended response

Check inventory. Check lockfiles and deployed manifests for istio.io/istio.
Review the reported fix. Update istio.io/istio to 0.0.0-20260403004500-692e460c342d if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Apr 16, 2026
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source description

### Impact 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 SA e.g. `cert-manager.io` also matches `cert-manager-io`, `cert-managerXio`, etc. A DENY rule targeting the same name fails to block those variants. ### Patches Fixes are available in 1.29.2, 1.28.6, and 1.27.9 ### Workarounds None

Quoted source text, attributed separately from HOL analysis.