medium 5.5

CVE-2025-21948 json

HID: appleir: Fix potential NULL dereference at raw event handle

published 2025-04-01 19 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-9373

cvss: 5.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits: 0; none known

In the Linux kernel, the following vulnerability has been resolved:

Syzkaller reports a NULL pointer dereference issue in input_event().

BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:68 [inline] BUG: KASAN: null-ptr-deref in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline] BUG: KASAN: null-ptr-deref in is_event_supported drivers/input/input.c:67 [inline] BUG: KASAN: null-ptr-deref in input_event+0x42/0xa0 drivers/input/input.c:395 Read of size 8 at addr 0000000000000028 by task syz-executor199/2949

CPU: 0 UID: 0 PID: 2949 Comm: syz-executor199 Not tainted 6.13.0-rc4-syzkaller-00076-gf097a36ef88d #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 kasan_report+0xd9/0x110 mm/kasan/report.c:602 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189 instrument_atomic_read include/linux/instrumented.h:68 [inline] _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline] is_event_supported drivers/input/input.c:67 [inline] input_event+0x42/0xa0 drivers/input/input.c:395 input_report_key include/linux/input.h:439 [inline] key_down drivers/hid/hid-appleir.c:159 [inline] appleir_raw_event+0x3e5/0x5e0 drivers/hid/hid-appleir.c:232 __hid_input_report.constprop.0+0x312/0x440 drivers/hid/hid-core.c:2111 hid_ctrl+0x49f/0x550 drivers/hid/usbhid/hid-core.c:484 __usb_hcd_giveback_urb+0x389/0x6e0 drivers/usb/core/hcd.c:1650 usb_hcd_giveback_urb+0x396/0x450 drivers/usb/core/hcd.c:1734 dummy_timer+0x17f7/0x3960 drivers/usb/gadget/udc/dummy_hcd.c:1993 __run_hrtimer kernel/time/hrtimer.c:1739 [inline] __hrtimer_run_queues+0x20a/0xae0 kernel/time/hrtimer.c:1803 hrtimer_run_softirq+0x17d/0x350 kernel/time/hrtimer.c:1820 handle_softirqs+0x206/0x8d0 kernel/softirq.c:561 __do_softirq kernel/softirq.c:595 [inline] invoke_softirq kernel/softirq.c:435 [inline] __irq_exit_rcu+0xfa/0x160 kernel/softirq.c:662 irq_exit_rcu+0x9/0x30 kernel/softirq.c:678 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0x90/0xb0 arch/x86/kernel/apic/apic.c:1049 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 __mod_timer+0x8f6/0xdc0 kernel/time/timer.c:1185 add_timer+0x62/0x90 kernel/time/timer.c:1295 schedule_timeout+0x11f/0x280 kernel/time/sleep_timeout.c:98 usbhid_wait_io+0x1c7/0x380 drivers/hid/usbhid/hid-core.c:645 usbhid_init_reports+0x19f/0x390 drivers/hid/usbhid/hid-core.c:784 hiddev_ioctl+0x1133/0x15b0 drivers/hid/usbhid/hiddev.c:794 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK>

This happens due to the malformed report items sent by the emulated device which results in a report, that has no fields, being added to the report list. Due to this appleir_input_configured() is never called, hidinput_connect() fails which results in the HID_CLAIMED_INPUT flag is not being set. However, it does not make appleir_probe() fail and lets the event callback to be called without the associated input device.

Thus, add a check for the HID_CLAIMED_INPUT flag and leave the event hook early if the driver didn't claim any input_dev for some reason. Moreover, some other hid drivers accessing input_dev in their event callbacks do have similar checks, too.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Patch / fix

fixed in 1 distros 4 links 8

Linux Linux 5.4.291, 5.10.235, 5.15.179, 6.1.131, 6.6.83, 6.12.19, 6.13.7, 6.14

debian ubuntu suse azure linux

linux Debian 12 6.1.133-1
linux Debian 14, Debian 13 6.12.19-1

debian advisories DEBIAN-CVE-2025-21948

linux Ubuntu 20.04 LTS 5.4.0-216.236
linux Ubuntu 22.04 LTS 5.15.0-140.150
linux Ubuntu 24.04 LTS 6.8.0-84.84
linux-aws Ubuntu 20.04 LTS 5.4.0-1146.156
linux-aws Ubuntu 22.04 LTS 5.15.0-1084.91
linux-aws Ubuntu 24.04 LTS 6.8.0-1039.41
linux-gcp Ubuntu 20.04 LTS 5.4.0-1149.158
linux-gcp Ubuntu 22.04 LTS 5.15.0-1083.92

ubuntu advisories UBUNTU-CVE-2025-21948

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
kernel-syms-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
kernel-source-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
kernel-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.39.1
kernel-syms-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.39.1
kernel-rt_debug Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.39.1
kernel-source-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.39.1
kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.3.1

suse advisories SUSE-SU-2025:01967-1 SUSE-SU-2025:01964-1 SUSE-SU-2025:01951-1 SUSE-SU-2025:01919-1 SUSE-SU-2025:01707-1 SUSE-SU-2025:01614-1

kernel Azure Linux 3.0 6.6.85.1-2
kernel CBL-Mariner 2.0 5.15.180.1-1

azure linux advisories AZL-59946 AZL-59960

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-21948 updated 2026-11-07 cvss 5.5

kernel: HID: appleir: Fix potential NULL dereference at raw event handle

Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
affected: no fix planned “Out of support scope”
Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
affected: no fix available “Fix deferred”
Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 13 mo ago (2025-10-01)

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

Linux Linux

Classification

Weakness

CWE-476 NULL Pointer Dereference

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2025-21948
NVD CVE-2025-21948

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary