CVE-2026-39350: Istio is an open platform to connect, manage, and secure microservices

Routine

MEDIUM 5.4UPGRADE

CVE-2026-39350 is a medium-severity flaw (CVSS 5.4) affecting istio. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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-m

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 89%)
CISA exploited list	No
Weakness	CWE-185, CWE-863
Published	2026-04-15
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: istio

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-15 23:16 UTCPublished CVE record published
2026-06-17 10:41 UTCUpdated Record last modified

istio istio UPGRADE

Affected: >= 1.25.0 and < 1.27.9 · >= 1.28.0 and < 1.28.6 · >= 1.29.0 and < 1.29.2

Fixed in: 1.27.9, 1.28.6, 1.29.2

Safe to downgrade to: a release before 1.25.0

1. Check installed version

apt-cache policy istio || rpm -q istio || istio --version

2. UPGRADE to 1.27.9 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade istio

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade istio

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.25.0 (Debian / Ubuntu)

apt-cache madison istio sudo apt install istio=<VERSION_BEFORE_1.25.0> sudo apt-mark hold istio

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list istio sudo dnf downgrade istio-<VERSION_BEFORE_1.25.0> sudo dnf versionlock add istio

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-39350?

istio: upgrade to 1.27.9, 1.28.6, 1.29.2. Exact commands for each OS are on this page.

Is CVE-2026-39350 being exploited?

CVE-2026-39350 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-39350 affect?

CVE-2026-39350 affects istio. Severity is medium (CVSS 5.4). 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 inter

How urgent is CVE-2026-39350?

Priority 22/100. No elevated risk signals yet.

Software pages

Istio vulnerabilities

Related CVEs

CVE-2026-41413 MEDIUM 5.0 UPGRADE Istio is an open platform to connect, manage, and secure microservices

References

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