Linux: Use After Free
CVE-2026-43237 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 e9e477d3197f7d8955a042c0d7f53f78f13218ba, 0399b8416ecf64ef86ad23401fe23eabdb07831a, bd8150a1b3370a9f7761c5814202a3fe5a79f44f 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 e9e477d3197f7d8955a042c0d7f53f78f13218ba or 0399b8416ecf64ef86ad23401fe23eabdb07831a or bd8150a1b3370a9f7761c5814202a3fe5a79f44f, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.16 or 6.19.6, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 70773bef4e091ff6d2a91e3dfb4f29013eb81f1f up to, but not including, e9e477d3197f7d8955a042c0d7f53f78f13218ba; 70773bef4e091ff6d2a91e3dfb4f29013eb81f1f up to, but not including, 0399b8416ecf64ef86ad23401fe23eabdb07831a; 70773bef4e091ff6d2a91e3dfb4f29013eb81f1f up to, but not including, bd8150a1b3370a9f7761c5814202a3fe5a79f44f; 6.16 | e9e477d3197f7d8955a042c0d7f53f78f13218ba, 0399b8416ecf64ef86ad23401fe23eabdb07831a, bd8150a1b3370a9f7761c5814202a3fe5a79f44f |
| Linux | Linux Kernel | 6.16 up to, but not including, 6.18.16; 6.19 up to, but not including, 6.19.6 | 6.18.16, 6.19.6 |
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 CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: Refactor amdgpu_gem_va_ioctl for Handling Last Fence Update and Timeline Management v4 This commit simplifies the amdgpu_gem_va_ioctl function, key updates include: - Moved the logic for managing the last update fence directly into amdgpu_gem_va_update_vm. - Introduced checks for the timeline point to enable conditional replacement or addition of fences. v2: Addressed review comments from Christian. v3: Updated comments (Christian). v4: The previous version selected the fence too early and did not manage its reference correctly, which could lead to stale or freed fences being used. This resulted in refcount underflows and could crash when updating GPU timelines. The fence is now chosen only after the VA mapping work is completed, and its reference is taken safely. After exporting it to the VM timeline syncobj, the driver always drops its local fence reference, ensuring balanced refcounting and avoiding use-after-free on dma_fence. Crash signature: [ 205.828135] refcount_t: underflow; use-after-free. [ 205.832963] WARNING: CPU: 30 PID: 7274 at lib/refcount.c:28 refcount_warn_saturate+0xbe/0x110 ... [ 206.074014] Call Trace: [ 206.076488] <TASK> [ 206.078608] amdgpu_gem_va_ioctl+0x6ea/0x740 [amdgpu] [ 206.084040] ? __pfx_amdgpu_gem_va_ioctl+0x10/0x10 [amdgpu] [ 206.089994] drm_ioctl_kernel+0x86/0xe0 [drm] [ 206.094415] drm_ioctl+0x26e/0x520 [drm] [ 206.098424] ? __pfx_amdgpu_gem_va_ioctl+0x10/0x10 [amdgpu] [ 206.104402] amdgpu_drm_ioctl+0x4b/0x80 [amdgpu] [ 206.109387] __x64_sys_ioctl+0x96/0xe0 [ 206.113156] do_syscall_64+0x66/0x2d0 ... [ 206.553351] BUG: unable to handle page fault for address: ffffffffc0dfde90 ... [ 206.553378] RIP: 0010:dma_fence_signal_timestamp_locked+0x39/0xe0 ... [ 206.553405] Call Trace: [ 206.553409] <IRQ> [ 206.553415] ? __pfx_drm_sched_fence_free_rcu+0x10/0x10 [gpu_sched] [ 206.553424] dma_fence_signal+0x30/0x60 [ 206.553427] drm_sched_job_done.isra.0+0x123/0x150 [gpu_sched] [ 206.553434] dma_fence_signal_timestamp_locked+0x6e/0xe0 [ 206.553437] dma_fence_signal+0x30/0x60 [ 206.553441] amdgpu_fence_process+0xd8/0x150 [amdgpu] [ 206.553854] sdma_v4_0_process_trap_irq+0x97/0xb0 [amdgpu] [ 206.554353] edac_mce_amd(E) ee1004(E) [ 206.554270] amdgpu_irq_dispatch+0x150/0x230 [amdgpu] [ 206.554702] amdgpu_ih_process+0x6a/0x180 [amdgpu] [ 206.555101] amdgpu_irq_handler+0x23/0x60 [amdgpu] [ 206.555500] __handle_irq_event_percpu+0x4a/0x1c0 [ 206.555506] handle_irq_event+0x38/0x80 [ 206.555509] handle_edge_irq+0x92/0x1e0 [ 206.555513] __common_interrupt+0x3e/0xb0 [ 206.555519] common_interrupt+0x80/0xa0 [ 206.555525] </IRQ> [ 206.555527] <TASK> ... [ 206.555650] RIP: 0010:dma_fence_signal_timestamp_locked+0x39/0xe0 ... [ 206.555667] Kernel panic - not syncing: Fatal exception in interrupt
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.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
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