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

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.

Published: 2025-06-06 Last update: 2026-01-08 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-0620 is rated Low Risk (36.2/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.25%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-0620

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-21 0.58% 0.25% -0.33%
2 2026-04-02 0.16% 0.58% +0.42%
3 2026-03-23 — 0.16% —

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-0620

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.2 3.6 [email protected]
4.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.2 3.6 [email protected]

Weakness enumeration for CVE-2025-0620

OS Trackers for CVE-2025-0620

vendor priority summary link
alpine — CVE-2025-0620: 1 source package rows (samba); 8 state rows across 2 repos (3.22-main, edge-main); fixed 2, open 6. https://security.alpinelinux.org/vuln/CVE-2025-0620
debian unimportant CVE-2025-0620 unimportant priority: Debian including 1 source packages (samba), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2025-0620
redhat medium — https://access.redhat.com/security/cve/CVE-2025-0620
suse medium — https://www.suse.com/security/cve/CVE-2025-0620/
ubuntu medium CVE-2025-0620 medium priority: Ubuntu including 1 source packages (samba), 9 status rows across 9 suites (bionic, focal, jammy, noble, oracular, plucky, trusty, upstream, xenial): not-affected 7, released 2. https://ubuntu.com/security/CVE-2025-0620

Affected software / configurations for CVE-2025-0620

Vendor Product Version Raw CPE
samba samba >= 4.21.0, < 4.21.6 cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
samba samba >= 4.22.0, < 4.22.2 cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*

References for CVE-2025-0620

cvelogic Threat Intelligence