Istio AuthorizationPolicy Incorrect Regex Matching of Dots in serviceAccounts Fields Allows Policy Bypass
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Partial Red Hat: 1 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-863.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| istio | istio | >= 1.25.0, < < 1.27.9; 1.28.0 to before 1.28.6; 1.29.0 to before 1.29.2 | 1.28.6, 1.29.2 | Patch available | CNA |
| — | istio.io/istio (Go) | 0.0.0-20241024090207-0bf27d49ba4b to before 0.0.0-20260403004500-692e460c342d | 0.0.0-20260403004500-692e460c342d | Patch available | GHSA-9gcg-w975-3rjh |
- istio Vendoristio Affected >= 1.25.0, < < 1.27.9; 1.28.0 to before 1.28.6; 1.29.0 to before 1.29.2 Fixed in 1.28.6, 1.29.2 Patch available CNA
- istio.io/istio (Go) Vendor— Affected 0.0.0-20241024090207-0bf27d49ba4b to before 0.0.0-20260403004500-692e460c342d Fixed in 0.0.0-20260403004500-692e460c342d Patch available GHSA-9gcg-w975-3rjh
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:istio:istio:*:*:*:*:*:*:*:* | 1.25.0 to before 1.27.9; 1.28.0 to before 1.28.6; 1.29.0 to before 1.29.2 | Vulnerable | istio |
- cpe:2.3:a:istio:istio:*:*:*:*:*:*:*:* Versions 1.25.0 to before 1.27.9; 1.28.0 to before 1.28.6; 1.29.0 to before 1.29.2 Vulnerable ·istio
Remediation
- Fix · CNA istio (istio) Fixed in 1.28.6, 1.29.2
- Fix · GHSA-9gcg-w975-3rjh istio.io/istio (Go) Fixed in 0.0.0-20260403004500-692e460c342d Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| OpenShift Service Mesh 3 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-39350
- 2026-10-03 Alias added: GHSA-9gcg-w975-3rjh
References
More Istio vulnerabilities
- TI-2026-79288 Out-of-bounds write in Google Brotli decoder KEVCVSS 4.0CRITICAL 9.2
- TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
- TI-2022-06055 Authorization Policy bypass in Istio CVSS 3.1CRITICAL 9.8
- TI-2021-11909 Istio before 1.8.6 and 1.9.x before 1.9.5 contains a remotely exploitable vulnerability… CVSS 3.1CRITICAL 9.8
- TI-2026-24390 Istio JWKS resolver to prevent private key material from being exposed when JWKS fetch fails. CVSS 4.0HIGH 8.7
- TI-2022-13090 Ill-formed headers may lead to unexpected behavior in Istio CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-39350 · CVE Program
- CVE-2026-39350 · NVD
- FIRST EPSS
- GHSA-9gcg-w975-3rjh · GitHub Advisory Database · CC BY 4.0
- CVE-2026-39350 · Red Hat security data · CC BY 4.0
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