CyberSecBulletin
CVE-2026-31426NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-31426 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.0 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 022d1727f33ff90b3e1775125264e3023901952e, 9c886e63b69658959633937e3acb7ca8addf7499, 808c0f156f48d5b8ca34088cbbfba8444e606cbc as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.15% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 022d1727f33ff90b3e1775125264e3023901952e or 9c886e63b69658959633937e3acb7ca8addf7499 or 808c0f156f48d5b8ca34088cbbfba8444e606cbc or d04c007047c88158141d9bd5eac761cdadd3782c, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.1.168 or 6.6.131 or 6.12.80 or 6.18.21, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux03e9a0e05739cf872fee494b06c75c0469704a21 up to, but not including, 022d1727f33ff90b3e1775125264e3023901952e; 03e9a0e05739cf872fee494b06c75c0469704a21 up to, but not including, 9c886e63b69658959633937e3acb7ca8addf7499; 03e9a0e05739cf872fee494b06c75c0469704a21 up to, but not including, 808c0f156f48d5b8ca34088cbbfba8444e606cbc; 03e9a0e05739cf872fee494b06c75c0469704a21 up to, but not including, d04c007047c88158141d9bd5eac761cdadd3782c; 03e9a0e05739cf872fee494b06c75c0469704a21 up to, but not including, be1a827e15991e874e0d5222d0ea5fdad01960fe; 03e9a0e05739cf872fee494b06c75c0469704a21 up to, but not including, f6484cadbcaf26b5844b51bd7307a663dda48ef6; 5.7022d1727f33ff90b3e1775125264e3023901952e, 9c886e63b69658959633937e3acb7ca8addf7499, 808c0f156f48d5b8ca34088cbbfba8444e606cbc, d04c007047c88158141d9bd5eac761cdadd3782c, be1a827e15991e874e0d5222d0ea5fdad01960fe, f6484cadbcaf26b5844b51bd7307a663dda48ef6
LinuxLinux Kernel5.7 up to, but not including, 6.1.168; 6.2 up to, but not including, 6.6.131; 6.7 up to, but not including, 6.12.80; 6.13 up to, but not including, 6.18.21; 6.19 up to, but not including, 6.19.11; 5.7; 7.06.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: ACPI: EC: clean up handlers on probe failure in acpi_ec_setup() When ec_install_handlers() returns -EPROBE_DEFER on reduced-hardware platforms, it has already started the EC and installed the address space handler with the struct acpi_ec pointer as handler context. However, acpi_ec_setup() propagates the error without any cleanup. The caller acpi_ec_add() then frees the struct acpi_ec for non-boot instances, leaving a dangling handler context in ACPICA. Any subsequent AML evaluation that accesses an EC OpRegion field dispatches into acpi_ec_space_handler() with the freed pointer, causing a use-after-free: BUG: KASAN: slab-use-after-free in mutex_lock (kernel/locking/mutex.c:289) Write of size 8 at addr ffff88800721de38 by task init/1 Call Trace: <TASK> mutex_lock (kernel/locking/mutex.c:289) acpi_ec_space_handler (drivers/acpi/ec.c:1362) acpi_ev_address_space_dispatch (drivers/acpi/acpica/evregion.c:293) acpi_ex_access_region (drivers/acpi/acpica/exfldio.c:246) acpi_ex_field_datum_io (drivers/acpi/acpica/exfldio.c:509) acpi_ex_extract_from_field (drivers/acpi/acpica/exfldio.c:700) acpi_ex_read_data_from_field (drivers/acpi/acpica/exfield.c:327) acpi_ex_resolve_node_to_value (drivers/acpi/acpica/exresolv.c:392) </TASK> Allocated by task 1: acpi_ec_alloc (drivers/acpi/ec.c:1424) acpi_ec_add (drivers/acpi/ec.c:1692) Freed by task 1: kfree (mm/slub.c:6876) acpi_ec_add (drivers/acpi/ec.c:1751) The bug triggers on reduced-hardware EC platforms (ec->gpe < 0) when the GPIO IRQ provider defers probing. Once the stale handler exists, any unprivileged sysfs read that causes AML to touch an EC OpRegion (battery, thermal, backlight) exercises the dangling pointer. Fix this by calling ec_remove_handlers() in the error path of acpi_ec_setup() before clearing first_ec. ec_remove_handlers() checks each EC_FLAGS_* bit before acting, so it is safe to call regardless of how far ec_install_handlers() progressed: -ENODEV (handler not installed): only calls acpi_ec_stop() -EPROBE_DEFER (handler installed): removes handler, stops EC

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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