CVE-2026-31718

Published May 1, 2026

Last updated 5 months ago

CVSS critical 9.8

Overview

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().
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Secondary
Base score
9.8
Impact score
5.9
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity
CRITICAL

Weaknesses

nvd@nist.gov
CWE-416

Social media

Hype score
Not currently trending

  1. 🚨 CRITICAL: CVE-2026-31718 (CVSS 9.8) Linux kernel ksmbd use-after-free flaw allows remote code execution via durable file handle scavenger. Affects network-attached storage implementations. Patch immediately. #CVE #Vulnerability #PatchNow https://t.co/P25G9ftF4y

    @DFIR_Lab

    23 May 2026

    55 Impressions

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  2. CRITICAL: CVE-2026-31718 (CVSS 9.8) — multiple products. CVE: CVE-2026-31718 CVSS: 9.8 (3.1) — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Severity: CRITICAL Status: Critical advisory

    @lyrie_ai

    12 May 2026

    38 Impressions

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Configurations

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References

Sources include official advisories and independent security research.