Critical severity · published May 1, 2026
CVE-2026-31718
ksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger
9.8
CVSS
0.4%
EPSS
No
On KEV
Description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger
When a durable file handle survives session disconnect (TCP close without
SMB2_LOGOFF), session_fd_check() sets fp->conn = NULL to preserve the
handle for later reconnection. However, it did not clean up the byte-range
locks on fp->lock_list.
Later, when the durable scavenger thread times out and calls
__ksmbd_close_fd(NULL, fp), the lock cleanup loop did:
spin_lock(&fp->conn->llist_lock);
This caused a slab use-after-free because fp->conn was NULL and the
original connection object had already been freed by
ksmbd_tcp_disconnect().
The root cause is asymmetric cleanup: lock entries (smb_lock->clist) were
left dangling on the freed conn->lock_list while fp->conn was nulled out.
To fix this issue properly, we need to handle the lifetime of
smb_lock->clist across three paths:
- Safely skip clist deletion when list is empty and fp->conn is NULL.
- Remove the lock from the old connection's lock_list in
session_fd_check()
- Re-add the lock to the new connection's lock_list in
ksmbd_reopen_durable_fd().
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 29% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KE
Kernel · Linux
6.6.32 before 6.7; 6.9 before 6.12.84; 6.13 before 6.18.25; 6.19 before 7.0.2; 7.1 · source: NVD
LI
Linux · Linux
8df4bcdb0a4232192b2445256c39b787d58ef14d before 0000a7780e0e446a28a273572f6ea8f7f582f694; c8efcc786146a951091588e5fa7e3c754850cb3c before e33c65f011980b4ad4abfd93585ec2079856368f; c8efcc786146a951091588e5fa7e3c754850cb3c before 3d6682726c2d3a46d31dae88b8166786b09b03ad; c8efcc786146a951091588e5fa7e3c754850cb3c before b34fc42cfe922e551f7a27d3ac3bb016e41d7dd9; c8efcc786146a951091588e5fa7e3c754850cb3c before 235e32320a470fcd3998fb3774f2290a0eb302a1; 6.6.32 before 6.6.140; +1 more · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-31718
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-31718
git.kernel.org
https://git.kernel.org/stable/c/0000a7780e0e446a28a273572f6ea8f7f582f694
Patch
https://git.kernel.org/stable/c/235e32320a470fcd3998fb3774f2290a0eb302a1
Patch
https://git.kernel.org/stable/c/3d6682726c2d3a46d31dae88b8166786b09b03ad
Patch
https://git.kernel.org/stable/c/b34fc42cfe922e551f7a27d3ac3bb016e41d7dd9
Patch
https://git.kernel.org/stable/c/e33c65f011980b4ad4abfd93585ec2079856368f
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