Linux: Use After Free
CVE-2026-46213 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 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 59a79938ca5541fe55d675304116b7ea684afef0, 93d989e47bc316c793a69c6a332e053c90e29f02, 4db2af929279c799b5653a39eb0795c72baffca4 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 0.12% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 59a79938ca5541fe55d675304116b7ea684afef0 or 93d989e47bc316c793a69c6a332e053c90e29f02 or 4db2af929279c799b5653a39eb0795c72baffca4 or 6.16, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.16 or 6.18.32 or 7.0.9, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 38224c472a038fa9ccd4085511dd9f3d6119dbf9 up to, but not including, 59a79938ca5541fe55d675304116b7ea684afef0; 38224c472a038fa9ccd4085511dd9f3d6119dbf9 up to, but not including, 93d989e47bc316c793a69c6a332e053c90e29f02; 38224c472a038fa9ccd4085511dd9f3d6119dbf9 up to, but not including, 4db2af929279c799b5653a39eb0795c72baffca4; 51720dee3a61ebace36c3dcdd0b4a488e0970f29; 6.15.6 up to, but not including, 6.16; 6.16 | 59a79938ca5541fe55d675304116b7ea684afef0, 93d989e47bc316c793a69c6a332e053c90e29f02, 4db2af929279c799b5653a39eb0795c72baffca4, 6.16 |
| Linux | Linux Kernel | 6.15.6 up to, but not including, 6.16; 6.16.1 up to, but not including, 6.18.32; 6.19 up to, but not including, 7.0.9; 6.16; 7.1 | 6.16, 6.18.32, 7.0.9 |
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
- LowNo special conditions are needed; the attack works reliably.
- 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:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
Official description
In the Linux kernel, the following vulnerability has been resolved: HID: appletb-kbd: fix UAF in inactivity-timer cleanup path Commit 38224c472a03 ("HID: appletb-kbd: fix slab use-after-free bug in appletb_kbd_probe") added timer_delete_sync(&kbd->inactivity_timer) to both the probe close_hw error path and appletb_kbd_remove(), but the way it was wired in left the inactivity timer reachable during driver tear-down via two distinct windows. Window A -- put_device() before timer_delete_sync(): put_device(&kbd->backlight_dev->dev); timer_delete_sync(&kbd->inactivity_timer); The inactivity_timer softirq reads kbd->backlight_dev and calls backlight_device_set_brightness() -> mutex_lock(&ops_lock). If a concurrent hid_appletb_bl unbind drops the last devm reference between these two calls, the backlight_device is freed and the mutex_lock() touches freed memory. Window B -- backlight cleanup before hid_hw_stop(): if (kbd->backlight_dev) { timer_delete_sync(...); put_device(...); } hid_hw_close(hdev); hid_hw_stop(hdev); Even after Window A is closed, hid_hw_close()/hid_hw_stop() still run afterwards, so a late ".event" callback from the HID core (USB URB completion on real Apple hardware) can arrive after timer_delete_sync() drained the softirq but before put_device() drops the reference. That callback reaches reset_inactivity_timer(), which calls mod_timer() and re-arms the timer. The freshly re-armed timer can then fire on the about-to-be-freed backlight_device. Both windows produce the same KASAN slab-use-after-free: BUG: KASAN: slab-use-after-free in __mutex_lock+0x1aab/0x21c0 Read of size 8 at addr ffff88803ee9a108 by task swapper/0/0 Call Trace: <IRQ> __mutex_lock backlight_device_set_brightness appletb_inactivity_timer call_timer_fn run_timer_softirq handle_softirqs Allocated by task N: devm_backlight_device_register appletb_bl_probe Freed by task M: (concurrent hid_appletb_bl unbind path) Close both windows at once by reworking the tear-down in appletb_kbd_remove() and in the probe close_hw error path so that 1) hid_hw_close()/hid_hw_stop() run before the backlight cleanup, guaranteeing no further .event callback can fire and re-arm the timer, and 2) inside the "if (kbd->backlight_dev)" block, timer_delete_sync() runs before put_device(), so the softirq is drained before the final reference is dropped.
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.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Use After Free vulnerabilities
- 8.3 High severity
- 8.8 High severity
- 8.3 High severity
- 8.3 High severity
- 8.8 High severity
- 7.5 High severity
Spotted an error? Tell us.