# CVE-2025-0620: Samba: smbd doesn't pick up group membership changes when re-authenticating an expired smb session

Status: published. Published: 2025-06-06. Updated: 2026-11-05.

A flaw was found in Samba. The smbd service daemon does not pick up group membership changes when re-authenticating an expired SMB session. This issue can expose file shares until clients disconnect and then connect again.

## Remediation

No remediation reported in collected sources

## Affected products and versions

-  /  (samba): ≥ 4.21.0; < 4.21.6 (affected, semver). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (samba): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (samba): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (samba4): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (samba): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (samba): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (samba): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-8): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 4.9 (medium); CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.80% as of 2026-11-05; percentile 56.79%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-552

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/security/cve/CVE-2025-0620 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2370453 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://www.samba.org/samba/security/CVE-2025-0620.html (CNA: redhat)

- http://www.openwall.com/lists/oss-security/2025/06/03/8 (ADP: CVE)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2025-0620; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2025-0620; retrieved 2026-11-05; source updated Not reported

Revision: 63f560090e1783ac14c44f5c0407bebd760d5b80c77c85cd02671743a6dacc89

Canonical: https://y2.dev/cve/CVE-2025-0620

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