CVE-2026-31718

CRITICAL EPSS 27.5%
Published May 1, 20261mo ago · Modified Jun 17, 20261w ago
9.8 CVSS 3.1
Critical
Find Similar
Published May 1, 2026 1mo ago
Last Modified Jun 17, 2026 1w ago

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 Details

Base Score
9.8
Exploitability
3.9
Impact
5.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
27.5% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-416 Use After Free Memory Safety

Affected Products 5

VendorProductVersionRange
linuxlinux_kernel*≥6.6.32  –  <6.7
linuxlinux_kernel*≥6.9  –  <6.12.84
linuxlinux_kernel*≥6.13  –  <6.18.25
linuxlinux_kernel*≥6.19  –  <7.0.2
linuxlinux_kernel7.1any

References 5

  • git.kernel.org https://git.kernel.org/stable/c/0000a7780e0e446a28a273572f6ea8f7f582f694
  • git.kernel.org https://git.kernel.org/stable/c/235e32320a470fcd3998fb3774f2290a0eb302a1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/3d6682726c2d3a46d31dae88b8166786b09b03ad
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b34fc42cfe922e551f7a27d3ac3bb016e41d7dd9
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e33c65f011980b4ad4abfd93585ec2079856368f
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/235e32320a470fcd3998fb3774f2290a0eb302a1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/3d6682726c2d3a46d31dae88b8166786b09b03ad
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b34fc42cfe922e551f7a27d3ac3bb016e41d7dd9
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e33c65f011980b4ad4abfd93585ec2079856368f
    Patch