ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-476.
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers smb2_oplock_break_noti() and smb2_lease_break_noti() read opinfo->conn into a local with neither READ_ONCE() nor a NULL check. Both run from oplock_break() after opinfo_get_list() has dropped ci->m_lock, so a concurrent SMB2 LOGOFF (session_fd_check()) can set op->conn = NULL under ci->m_lock within that window. ksmbd_conn_r_count_inc(conn) then writes through NULL at offset 0xc4 -- a remotely triggerable oops. Guard both reads the way compare_guid_key() already does: read opinfo->conn with READ_ONCE() and return early if it is NULL, before allocating the work struct so nothing leaks. A NULL conn means the client is gone and the break is moot, so return 0; oplock_break() treats that as success and runs the normal teardown.
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 | 6.6.32 to before 6.6.143 | 6.6.143 | Patch available | CNA |
| Linux | Linux | 6.9 and later | 6.6.143, 6.12.94, 6.18.36, 7.0.13, 7.1 | Patch available | CNA |
- Linux VendorLinux Affected 6.6.32 to before 6.6.143 Fixed in 6.6.143 Patch available CNA
- Linux VendorLinux Affected 6.9 and later Fixed in 6.6.143, 6.12.94, 6.18.36, 7.0.13, 7.1 Patch available CNA
CPE configurations NVD · 7
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 6.6.32 to before 6.6.143; 6.9 to before 6.12.94; 6.13 to before 6.18.36; 6.19 to before 7.0.13 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* | 7.1 rc1 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* | 7.1 rc2 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* | 7.1 rc3 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* | 7.1 rc4 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* | 7.1 rc5 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:* | 7.1 rc6 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 6.6.32 to before 6.6.143; 6.9 to before 6.12.94; 6.13 to before 6.18.36; 6.19 to before 7.0.13 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* Versions 7.1 rc1 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* Versions 7.1 rc2 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* Versions 7.1 rc3 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* Versions 7.1 rc4 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* Versions 7.1 rc5 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:* Versions 7.1 rc6 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.6.143
- Fix · CNA Linux (Linux) Fixed in 6.6.143, 6.12.94, 6.18.36, 7.0.13, 7.1
Vendor assessments
Red Hat
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-2026-53271
- 2026-10-03 Alias added: GHSA-hxmm-jmj9-253j
References
Patch 5
- https://git.kernel.org/stable/c/945a86b21b40fb17183f5b27461baa6f03e2467f
- https://git.kernel.org/stable/c/1ff58dcfcab434ebb51649da33774fbb8e1f7b67
- https://git.kernel.org/stable/c/e735dbd489e3ea02be78dba991056fe1138be51e
- https://git.kernel.org/stable/c/75e33deda658c1ab3a9336cbdb1436536f9b3660
- https://git.kernel.org/stable/c/b003086d76968298f22e7cf62239833b5a3a06b1
More Linux Kernel vulnerabilities
- TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
- TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
- TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
Sources
- CVE-2026-53271 · CVE Program
- CVE-2026-53271 · NVD
- FIRST EPSS
- GHSA-hxmm-jmj9-253j · GitHub Advisory Database · CC BY 4.0
- CVE-2026-53271 · 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