ksmbd: do not expire session on binding failure
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA.
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: do not expire session on binding failure When a multichannel session binding request fails (e.g. wrong password), the error path unconditionally sets sess->state = SMB2_SESSION_EXPIRED. However, during binding, sess points to the target session looked up via ksmbd_session_lookup_slowpath() -- which belongs to another connection's user. This allows a remote attacker to invalidate any active session by simply sending a binding request with a wrong password (DoS). Fix this by skipping session expiration when the failed request was a binding attempt, since the session does not belong to the current connection. The reference taken by ksmbd_session_lookup_slowpath() is still correctly released via ksmbd_user_session_put().
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 |
|---|---|---|---|---|---|
| Linux | Linux | 5.15 and later | 5.15.209, 6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11, 7.0 | Patch available | CNA |
- Linux VendorLinux Affected 5.15 and later Fixed in 5.15.209, 6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11, 7.0 Patch available CNA
CPE configurations NVD · 9
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 5.15.1 to before 6.1.168; 6.2 to before 6.6.131; 6.7 to before 6.12.80; 6.13 to before 6.18.21; 6.19 to before 6.19.11 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.15:-:*:*:*:*:*:* | 5.15 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* | 7.0 rc1 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* | 7.0 rc2 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* | 7.0 rc3 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* | 7.0 rc4 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* | 7.0 rc5 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:* | 7.0 rc6 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:* | 7.0 rc7 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.15.1 to before 6.1.168; 6.2 to before 6.6.131; 6.7 to before 6.12.80; 6.13 to before 6.18.21; 6.19 to before 6.19.11 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.15:-:*:*:*:*:*:* Versions 5.15 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* Versions 7.0 rc1 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* Versions 7.0 rc2 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* Versions 7.0 rc3 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* Versions 7.0 rc4 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* Versions 7.0 rc5 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:* Versions 7.0 rc6 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:* Versions 7.0 rc7 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.15.209, 6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11, 7.0
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
Not affected: 5 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2026-31476
- 2026-10-03 Alias added: GHSA-223f-gch2-xvq3
- 2026-10-20 Affected versions changed · Red Hat
- 2026-10-25 EPSS moved to the below the 50th percentile
References
Patch 6
- https://git.kernel.org/stable/c/f5300690c23c5ac860499bb37dbc09cf43fd62e6
- https://git.kernel.org/stable/c/6fafc4c4238e538969f1375f9ecdc6587c53f1cc
- https://git.kernel.org/stable/c/1d1888b4a7aec518b707f6eca0bf08992c0e8da3
- https://git.kernel.org/stable/c/a897064a457056acb976e20e3007cdf553de340f
- https://git.kernel.org/stable/c/e0e5edc81b241c70355217de7e120c97c3429deb
- https://git.kernel.org/stable/c/9bbb19d21ded7d78645506f20d8c44895e3d0fb9
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Sources
- CVE-2026-31476 · CVE Program
- CVE-2026-31476 · NVD
- FIRST EPSS
- GHSA-223f-gch2-xvq3 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-31476 · Red Hat security data · CC BY 4.0
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