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
- Jun 6, 2025
- Updated
- Aug 31, 2026
- EPSS
- 0.7% · 53th percentile
- CWE
- CWE-552
Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.
Report tools
Action score
19
Monitor
Low priority for now.
- CVSS
- 19 / 40 · 4.9 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.7%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · redhat
- 4.9
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| samba | samba | cpe:2.3:a:samba:samba |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- samba samba4.21.0 and later · before 4.21.6
- samba samba4.22.0 and later · before 4.22.2
Versions reported by the vendor
Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.
Red Hat Red Hat Enterprise Linux 10
- all versionsaffected
Red Hat Red Hat Enterprise Linux 6
- all versionsunknown
- all versionsunknown
Red Hat Red Hat Enterprise Linux 7
- all versionsunknown
Red Hat Red Hat Enterprise Linux 8
- all versionsunknown
Red Hat Red Hat Enterprise Linux 9
- all versionsaffected
Red Hat Red Hat OpenShift Container Platform 4
- all versionsunknown
- all versionsunknown
www.samba.org/ samba
- 4.21.0 and later · before 4.21.6affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.22 | samba | from 4.21.0 · before 4.21.6-r0 | 4.21.6-r0 |
| Debian:13 | samba | before 2:4.22.2+dfsg-1 | 2:4.22.2+dfsg-1 |
| openSUSE:Tumbleweed | samba | before 4.22.2+git.396.c752843dcf4-1.1 | 4.22.2+git.396.c752843dcf4-1.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | samba | before 4.21.6+git.402.80f493f530f-150700.3.3.1 | 4.21.6+git.402.80f493f530f-150700.3.3.1 |
Same product
samba: all recordsOther highest-scoring records for the same primary product.
- CVE-2017-7494Samba since version 3.5.0 and before 4.6.4, 4.5.10 and 4.4.14 is vulnerable to remote code execution vulnerability, allowing a malicious cliKEV99Now
- CVE-2015-0240The Netlogon server implementation in smbd in Samba 3.5.x and 3.6.x before 3.6.25, 4.0.x before 4.0.25, 4.1.x before 4.1.17, and 4.2.x befor66This week
- CVE-2003-0085Buffer overflow in the SMB/CIFS packet fragment re-assembly code for SMB daemon (smbd) in Samba before 2.2.8, and Samba-TNG before 0.3.1, al66This week
- CVE-2003-0201Buffer overflow in the call_trans2open function in trans2.c for Samba 2.2.x before 2.2.8a, 2.0.10 and earlier 2.0.x versions, and Samba-TNG 65This week
- CVE-2007-2446Multiple heap-based buffer overflows in the NDR parsing in smbd in Samba 3.0.0 through 3.0.25rc3 allow remote attackers to execute arbitrary63This week
- CVE-2012-1182The RPC code generator in Samba 3.x before 3.4.16, 3.5.x before 3.5.14, and 3.6.x before 3.6.4 does not implement validation of an array len62This week
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| www.samba.org/ samba | 4.21.6 | Vendor (CNA) |
| alpine:samba | 4.21.6-r0 · Alpine:v3.22 | Package registry (OSV) |
| debian:samba | 2:4.22.2+dfsg-1 · Debian:13 | Package registry (OSV) |
| opensuse:samba | 4.22.2+git.396.c752843dcf4-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| suse:samba | 4.21.6+git.402.80f493f530f-150700.3.3.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP7 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- Administrator privileges are required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-552 · Files or Directories Accessible to External PartiesCVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
- OS Credential DumpingT1003
- Data from Network Shared DriveT1039
- Automated CollectionT1119
- Data from Information RepositoriesT1213
- Data from Cloud Storage ObjectT1530
- Unsecured Credentials: Credentials in FilesT1552.001
- Unsecured Credentials: Bash HistoryT1552.003
- Unsecured Credentials: Private KeysT1552.004
- Unsecured Credentials: Group Policy PreferencesT1552.006
- Credentials from Password StoresT1555
- Data from Configuration RepositoryT1602
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- access.redhat.com/security/cve/CVE-2025-0620
- bugzilla.redhat.com/show_bug.cgi?id=2370453
- www.samba.org/samba/security/CVE-2025-0620.html
- www.openwall.com/lists/oss-security/2025/06/03/8
Vendor advisories and official records. Exploit/PoC links are deliberately left out.