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IstioApplication

CVE-2026-39350

MEDIUM · 5.4 CVSS v3.1 Published 2026-04-15
Fix available
A fix is available. Upgrade to 1.27.9 / 1.28.6 or later.
See remediation →
60/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The Istio AuthorizationPolicy incorrectly interprets dots (.) in serviceAccounts and notServiceAccounts fields as regex metacharacters instead of literal characters. This causes ALLOW rules to match unintended service accounts (e.g., a rule for 'cert-manager.io' also allows 'cert-manager-io' and 'cert-managerXio') and DENY rules to fail blocking those same variants, resulting in both unintended access and ineffective restrictions.

MitigationUpgrade Istio to version 1.29.2, 1.28.6, or 1.27.9 (or later) which properly treats dots as literal characters in service account name matching.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
IstioApplication
Affected:>= 1.25.0, < 1.27.9>= 1.28.0, < 1.28.6>= 1.29.0, < 1.29.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Istio version
    Run 'istioctl version' or check the istiod deployment image version
    Affected if Version is >= 1.25.0 and < 1.27.9, or >= 1.28.0 and < 1.28.6, or >= 1.29.0 and < 1.29.2
  2. Identify AuthorizationPolicy resources with serviceAccounts field
    Run 'kubectl get authorizationpolicies -A -o json' and inspect the 'spec'->'selector'->'matchLabels' or 'spec'->'action' sections for presence of 'serviceAccounts' field
    Affected if Any AuthorizationPolicy resource contains a 'serviceAccounts' array with entries that include dots in the service account names
  3. Identify AuthorizationPolicy resources with notServiceAccounts field
    Run 'kubectl get authorizationpolicies -A -o json' and inspect for 'notServiceAccounts' field in the spec
    Affected if Any AuthorizationPolicy resource contains a 'notServiceAccounts' array with entries that include dots in the service account names
  4. Verify affected policies are actively applied
    Check that the identified AuthorizationPolicies have an 'action' field set to 'ALLOW' or 'DENY' and are not in a disabled state
    Affected if Policies with dots in serviceAccounts or notServiceAccounts are in ALLOW or DENY action mode and actively enforced

The environment is affected if Istio version is in the vulnerable range AND AuthorizationPolicy resources exist with dots in serviceAccounts or notServiceAccounts fields, causing overly permissive ALLOW matches or ineffective DENY rules.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.27.9 / 1.28.6 / 1.29.2 or later
Fixed in 1.27.91.28.61.29.2
Interim mitigation

Upgrade Istio to version 1.29.2, 1.28.6, or 1.27.9 (or later) which properly treats dots as literal characters in service account name matching.

Recommended fix High confidence

Istio 1.27.9, 1.28.6, or 1.29.2 (choose based on your current minor version)

  1. Identify your current Istio version using `istioctl version` or checking your control plane version
  2. Select the appropriate fixed version based on your current branch: 1.27.x -> upgrade to 1.27.9; 1.28.x -> upgrade to 1.28.6; 1.29.x -> upgrade to 1.29.2
  3. Upgrade Istio control plane using your deployment method (e.g., istioctl upgrade, Helm, or operator)
  4. Verify the upgrade completed successfully with `istioctl version`
  5. Review existing AuthorizationPolicy resources using serviceAccounts or notServiceAccounts fields containing dots in names; escape dots as `\.` if explicitly using regex matching, or use the fixed version which treats dots as literal characters by default
  6. Test that AuthorizationPolicy rules now correctly differentiate between similar service account names (e.g., cert-manager.io vs cert-manager-io)
Caveat Review release notes for your target version for any potential breaking changes; minor version upgrades within the same branch typically have low risk

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Istio Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-39350 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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