Use after free in samba
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-416 and the CVSS impact.
Summary
In DCE/RPC it is possible to share the handles (cookies for resource state) between multiple connections via a mechanism called 'association groups'. These handles can reference connections to our sam.ldb database. However while the database was correctly shared, the user credentials state was only pointed at, and when one connection within that association group ended, the database would be left pointing at an invalid 'struct session_info'. The most likely outcome here is a crash, but it is possible that the use-after-free could instead allow different user state to be pointed at and this might allow more privileged access.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | samba | Affects all versions since samba 4.0 | Fixedin samba v4.15.2, v4.14.10 and v4.13.14 | — | No fix listed | CNA |
- samba Vendor— Affected Affects all versions since samba 4.0 | Fixedin samba v4.15.2, v4.14.10 and v4.13.14 Fixed in — No fix listed CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:* | 4.0.0 to before 4.13.14; 4.14.0 to before 4.14.10; 4.15.0 to before 4.15.2 | Vulnerable | Samba |
- cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:* Versions 4.0.0 to before 4.13.14; 4.14.0 to before 4.14.10; 4.15.0 to before 4.15.2 Vulnerable ·Samba
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 5 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat Storage 3
Timeline
- 2026-10-02 Threatist record created from CVE-2021-3738
- 2026-10-03 Alias added: GHSA-jrfc-f73c-qmrr
References
More Samba vulnerabilities
- TI-2020-01431 Netlogon Elevation of Privilege Vulnerability KEVCVSS 3.1CRITICAL 10.0
- TI-2017-05139 Code injection in samba KEVCVSS 3.1CRITICAL 9.8
- TI-2015-00210 The Netlogon server implementation in smbd in Samba 3.5.x and 3.6.x before 3.6.25, 4.0.x… CVSS 2.0HIGH 10.0
- TI-2003-00081 Buffer overflow in the SMB/CIFS packet fragment re-assembly code for SMB daemon (smbd) in… CVSS 2.0HIGH 10.0
- TI-2003-00185 Buffer overflow in the call_trans2open function in trans2.c for Samba 2.2.x before… CVSS 2.0HIGH 10.0
- TI-2007-02362 Multiple heap-based buffer overflows in the NDR parsing in smbd in Samba 3.0.0 through… CVSS 2.0HIGH 10.0
Sources
- CVE-2021-3738 · CVE Program
- CVE-2021-3738 · NVD
- FIRST EPSS
- GHSA-jrfc-f73c-qmrr · GitHub Advisory Database · CC BY 4.0
- CVE-2021-3738 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences