CVE-2026-39350 Istio AuthorizationPolicy Incorrect Regex Matching of Dots in serviceAccounts Fields Allows Policy Bypass
Attackers can bypass Istio AuthorizationPolicy rules by exploiting regex dot matching in service account names, allowing unauthorized access.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-39350?
CVE-2026-39350 is a medium-severity authentication bypass vulnerability in istio, published on 15 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-39350?
3 open source packages ship an affected version, including istio.io/istio. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
istio.io/istio Go | From 0.0.0-20241024090207-0bf27d49ba4b | 0.0.0-20260403004500-692e460c342d |
istio.io/istio Go | From 0.0.0-20241024090207-0bf27d49ba4b | 0.0.0-20260403004500-692e460c342d |
istio.io/istio Go | From 0.0.0-20241024090207-0bf27d49ba4b | 0.0.0-20260403004500-692e460c342d |
Products include Istio Istio.
How do I fix CVE-2026-39350?
Upgrade istio.io/istio to 0.0.0-20260403004500-692e460c342d or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-39350 being exploited?
There is no known exploitation of CVE-2026-39350 in the wild and no public exploit code.
Other vulnerabilities in istio
- CVE-2021-31921 Missing authorization in n/a
- CVE-2021-34824 Information disclosure in n/a
- CVE-2026-31837 Istio JWKS resolver to prevent private key material from being exposed when JWKS fetch fails.
- CVE-2021-39155 Authorization Policy Bypass Due to Case Insensitive Host Comparison
- CVE-2021-39156 Fragments in Path May Lead to Authorization Policy Bypass
Sources
Also known as GHSA-9gcg-w975-3rjh, GO-2026-5289, MINI-257f-5q98-xp4m, MINI-2jgm-xwfj-cvjf, MINI-5xgg-cxmw-fcp6, MINI-6g8r-4663-4355 and 8 more.