CVE-2026-31446

HIGH EPSS 3.1%
Published Apr 22, 20262mo ago · Modified Jun 17, 20261w ago
7.8 CVSS 3.1
High
Find Similar
Published Apr 22, 2026 2mo ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix use-after-free in update_super_work when racing with umount Commit b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") moved ext4_unregister_sysfs() before flushing s_sb_upd_work to prevent new error work from being queued via /proc/fs/ext4/xx/mb_groups reads during unmount. However, this introduced a use-after-free because update_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which accesses the kobject's kernfs_node after it has been freed by kobject_del() in ext4_unregister_sysfs(): update_super_work ext4_put_super ----------------- -------------- ext4_unregister_sysfs(sb) kobject_del(&sbi->s_kobj) __kobject_del() sysfs_remove_dir() kobj->sd = NULL sysfs_put(sd) kernfs_put() // RCU free ext4_notify_error_sysfs(sbi) sysfs_notify(&sbi->s_kobj) kn = kobj->sd // stale pointer kernfs_get(kn) // UAF on freed kernfs_node ext4_journal_destroy() flush_work(&sbi->s_sb_upd_work) Instead of reordering the teardown sequence, fix this by making ext4_notify_error_sysfs() detect that sysfs has already been torn down by checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call in that case. A dedicated mutex (s_error_notify_mutex) serializes ext4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs() to prevent TOCTOU races where the kobject could be deleted between the state_in_sysfs check and the sysfs_notify() call.

CVSS Details

Base Score
7.8
Exploitability
1.8
Impact
5.9
Vector string
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required None
User Interaction Required
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
3.1% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-416 Use After Free Memory Safety

Affected Products 19

VendorProductVersionRange
linuxlinux_kernel*≥5.10.114  –  <5.11
linuxlinux_kernel*≥5.15.38  –  <5.15.203
linuxlinux_kernel*≥5.17.6  –  <5.18
linuxlinux_kernel*≥5.18.1  –  <6.1.168
linuxlinux_kernel*≥6.2  –  <6.6.131
linuxlinux_kernel*≥6.7  –  <6.12.80
linuxlinux_kernel*≥6.13  –  <6.18.21
linuxlinux_kernel*≥6.19  –  <6.19.11
linuxlinux_kernel5.18any
linuxlinux_kernel5.18any
linuxlinux_kernel5.18any
linuxlinux_kernel5.18any
linuxlinux_kernel5.18any
linuxlinux_kernel5.18any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any

References 7

  • git.kernel.org https://git.kernel.org/stable/c/034053378dd81837fd6c7a43b37ee2e58d4f0b4e
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/08b10e6f37fc533a759e9833af0692242e8b3f93
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/9449f99ba04f5dd1c8423ad8a90b3651d7240d1d
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c4d829737329f2290dd41e290b7d75effdb2a7ff
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c8fe17a1b308c3d8c703ebfb049b325f844342c3
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c97e282f7bfd0c3554c63d289964a5ca6a1d2ffe
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d15e4b0a418537aafa56b2cb80d44add83e83697
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/034053378dd81837fd6c7a43b37ee2e58d4f0b4e
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/08b10e6f37fc533a759e9833af0692242e8b3f93
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/9449f99ba04f5dd1c8423ad8a90b3651d7240d1d
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c4d829737329f2290dd41e290b7d75effdb2a7ff
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c8fe17a1b308c3d8c703ebfb049b325f844342c3
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c97e282f7bfd0c3554c63d289964a5ca6a1d2ffe
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d15e4b0a418537aafa56b2cb80d44add83e83697
    Patch