CVE-2025-0620Network attack vectorHinoki check available

Persistent share access via stale impersonation cache

Published Jun 6, 2025 · Updated Aug 31, 2026

Authorization bypass in Samba 4.21.0 through 4.21.5 allows remote authenticated users to retain access to SMB file shares. The smbd share-connection cache keeps associations with stale impersonation data and fails to replace them with current group membership after Kerberos session re-authentication. Exploitation requires Kerberos authentication, an existing SMB session, and removal from an authorized group; share access persists until a new connection.

CVSS severity4.9
Medium
EPSS probability0.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Authorization bypass in Samba 4.21.0 through 4.21.5 allows remote authenticated users to retain access to SMB file shares. The smbd share-connection cache keeps associations with stale impersonation data and fails to replace them with current group membership after Kerberos session re-authentication. Exploitation requires Kerberos authentication, an existing SMB session, and removal from an authorized group; share access persists until a new connection.

The record

CVE
CVE-2025-0620
Published
Jun 6, 2025
Updated
Aug 31, 2026
Vendor
PPP Project
Product
Samba
Classifications
CWE-552
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 6, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 31, 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=4.21.0 <4.21.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

PPP Project · Sambaversion=4.21.0 <4.21.6
389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.

Published CVSS scores

7.0Samba TeamCVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
4.9Red Hat, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/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-552Files or Directories Accessible to External Parties

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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