CVE-2026-31426High· 7.0▾ TwilightIn 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 …
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 38.5 · likelihood 0 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Exploit-prediction probability, daily snapshots since Oct 16.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
0.2%
Last analysed / modified upstream
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
Linux >= 03e9a0e05739cf872fee494b06c75c0469704a21 < 022d1727f33ff90b3e1775125264e3023901952eLinux >= 03e9a0e05739cf872fee494b06c75c0469704a21 < 9c886e63b69658959633937e3acb7ca8addf7499Linux >= 03e9a0e05739cf872fee494b06c75c0469704a21 < 808c0f156f48d5b8ca34088cbbfba8444e606cbcLinux >= 03e9a0e05739cf872fee494b06c75c0469704a21 < d04c007047c88158141d9bd5eac761cdadd3782cLinux >= 03e9a0e05739cf872fee494b06c75c0469704a21 < be1a827e15991e874e0d5222d0ea5fdad01960feLinux >= 03e9a0e05739cf872fee494b06c75c0469704a21 < f6484cadbcaf26b5844b51bd7307a663dda48ef6Linux 5.7Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
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