CVE-2026-39350Network attack vector

Authorization bypass via unescaped service-account dots

Published Apr 15, 2026 · Updated Apr 15, 2026

Authorization bypass in affected Istio releases allows remote authenticated users to cross service-account policy boundaries. AuthorizationPolicy compiles dots in serviceAccounts and notServiceAccounts values as regex wildcards instead of literal service-account characters. The flaw matters when mTLS-backed policies contain dots: a similarly named account can pass an ALLOW rule or evade a DENY rule, exposing only resources protected by that policy.

CVSS severity5.4
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in affected Istio releases allows remote authenticated users to cross service-account policy boundaries. AuthorizationPolicy compiles dots in serviceAccounts and notServiceAccounts values as regex wildcards instead of literal service-account characters. The flaw matters when mTLS-backed policies contain dots: a similarly named account can pass an ALLOW rule or evade a DENY rule, exposing only resources protected by that policy.

The record

CVE
CVE-2026-39350
Published
Apr 15, 2026
Updated
Apr 15, 2026
Vendor
Istio
Product
Istio
Classifications
CWE-185, CWE-863
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 1.25.0, < < 1.27.9
  2. Affected versionversion=>= 1.28.0, < 1.28.6
  3. Affected versionversion=>= 1.29.0, < 1.29.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Istio · Istioversion=>= 1.25.0, < < 1.27.9; version=>= 1.28.0, < 1.28.6; version=>= 1.29.0, < 1.29.2

Published CVSS scores

5.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-185Incorrect Regular Expression
CWE-863Incorrect Authorization

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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