Linux: Use After Free
CVE-2026-63884 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 df73f3bc731af1c39ac5405bc59c4e7c6f8e9117, 28b22dbaf407598cb3bb1d2c586a6f8018690ac2, 073bcbc95e9648c976da1654c7590a8d6ee12c2d 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 0.18% 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 df73f3bc731af1c39ac5405bc59c4e7c6f8e9117 or 28b22dbaf407598cb3bb1d2c586a6f8018690ac2 or 073bcbc95e9648c976da1654c7590a8d6ee12c2d or c9ae7e7e3bc98615364313b08d7acea5239ded0b, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.176 or 6.6.143 or 6.12.93 or 6.18.35, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 7ae034590ceaefd4d37465e3434877acfbadf411 up to, but not including, df73f3bc731af1c39ac5405bc59c4e7c6f8e9117; 7ae034590ceaefd4d37465e3434877acfbadf411 up to, but not including, 28b22dbaf407598cb3bb1d2c586a6f8018690ac2; 7ae034590ceaefd4d37465e3434877acfbadf411 up to, but not including, 073bcbc95e9648c976da1654c7590a8d6ee12c2d; 7ae034590ceaefd4d37465e3434877acfbadf411 up to, but not including, c9ae7e7e3bc98615364313b08d7acea5239ded0b; 7ae034590ceaefd4d37465e3434877acfbadf411 up to, but not including, a29654d451bbffe63d584a4cf64ad0efce6bcf1c; 7ae034590ceaefd4d37465e3434877acfbadf411 up to, but not including, 5c4063c87a619e4df954c179d24628636f5db15f; 5.17 | df73f3bc731af1c39ac5405bc59c4e7c6f8e9117, 28b22dbaf407598cb3bb1d2c586a6f8018690ac2, 073bcbc95e9648c976da1654c7590a8d6ee12c2d, c9ae7e7e3bc98615364313b08d7acea5239ded0b, a29654d451bbffe63d584a4cf64ad0efce6bcf1c, 5c4063c87a619e4df954c179d24628636f5db15f |
| Linux | Linux Kernel | 5.17 up to, but not including, 6.1.176; 6.2 up to, but not including, 6.6.143; 6.7 up to, but not including, 6.12.93; 6.13 up to, but not including, 6.18.35; 6.19 up to, but not including, 7.0.12; 7.1 | 6.1.176, 6.6.143, 6.12.93, 6.18.35, 7.0.12 |
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/i915: Fix potential UAF in TTM object purge TLDR: The bo->ttm object might be changed by calling ttm_bo_validate(), move casting it to an i915_tt object later to actually get the right pointer. A user reported hitting the following bug under heavy use on DG2: [26620.095550] Oops: general protection fault, probably for non-canonical address 0xa56b6b6b6b6b6b8b: 0000 1 SMP NOPTI [26620.095556] CPU: 2 UID: 0 PID: 631 Comm: Xorg Not tainted 6.18.8 #1 PREEMPT(lazy) [26620.095558] Hardware name: ASRock B850M Steel Legend WiFi/B850M Steel Legend WiFi, BIOS 3.50 09/18/2025 [26620.095559] RIP: 0010:i915_ttm_purge+0x84/0x100 [i915] [26620.095604] Code: 00 00 00 48 8d 54 24 10 48 89 e6 48 89 fb e8 83 aa ae ff 85 c0 75 6f 48 83 bb a8 01 00 00 00 74 2c 48 8b 45 78 48 85 c0 74 23 <48> 8b 78 20 48 c7 c2 ff ff ff ff 31 f6 e8 7a 73 e3 e0 48 8b 7d 78 [26620.095605] RSP: 0018:ffffc90005fd7430 EFLAGS: 00010282 [26620.095607] RAX: a56b6b6b6b6b6b6b RBX: ffff8881f46c3dc0 RCX: 0000000000000000 [26620.095608] RDX: 0000000000000000 RSI: 0000000000000246 RDI: 00000000ffffffff [26620.095609] RBP: ffff888289610f00 R08: 0000000000000001 R09: ffff88823b022000 [26620.095609] R10: ffff888103029b28 R11: ffff8881fc7f3800 R12: ffff88810b6150d0 [26620.095609] R13: ffff888289610f00 R14: 0000000000000000 R15: ffff8881f46c3dc0 [26620.095610] FS: 00007f1004d86900(0000) GS:ffff88901c858000(0000) knlGS:0000000000000000 [26620.095611] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [26620.095611] CR2: 00007f0fdf489000 CR3: 000000035b0c1000 CR4: 0000000000750ef0 [26620.095612] PKRU: 55555554 [26620.095612] Call Trace: [26620.095615] <TASK> [26620.095615] i915_ttm_move+0x2b9/0x420 [i915] [26620.095642] ? ttm_tt_init+0x65/0x80 [ttm] [26620.095644] ? i915_ttm_tt_create+0xc6/0x150 [i915] [26620.095667] ttm_bo_handle_move_mem+0xb6/0x160 [ttm] [26620.095669] ttm_bo_evict+0x100/0x150 [ttm] [26620.095671] ? preempt_count_add+0x64/0xa0 [26620.095673] ? _raw_spin_lock+0xe/0x30 [26620.095675] ? _raw_spin_unlock+0xd/0x30 [26620.095675] ? i915_gem_object_evictable+0xb7/0xd0 [i915] [26620.095704] ttm_bo_evict_cb+0x6e/0xd0 [ttm] [26620.095705] ttm_lru_walk_for_evict+0xa6/0x200 [ttm] [26620.095708] ttm_bo_alloc_resource+0x185/0x4f0 [ttm] [26620.095709] ? init_object+0x62/0xd0 [26620.095712] ttm_bo_validate+0x7a/0x180 [ttm] [26620.095713] ? _raw_spin_unlock_irqrestore+0x16/0x30 [26620.095714] __i915_ttm_get_pages+0xb0/0x170 [i915] [26620.095737] i915_ttm_get_pages+0x9f/0x150 [i915] [26620.095759] ? i915_gem_do_execbuffer+0xedc/0x2b40 [i915] [26620.095786] ? alloc_debug_processing+0xd0/0x100 [26620.095787] ? _raw_spin_unlock_irqrestore+0x16/0x30 [26620.095788] ? i915_vma_instance+0xa0/0x4e0 [i915] [26620.095822] __i915_gem_object_get_pages+0x2f/0x40 [i915] [26620.095848] i915_vma_pin_ww+0x706/0x980 [i915] [26620.095875] ? i915_gem_do_execbuffer+0xedc/0x2b40 [i915] [26620.095904] eb_validate_vmas+0x170/0xa00 [i915] [26620.095930] i915_gem_do_execbuffer+0x1201/0x2b40 [i915] [26620.095953] ? alloc_debug_processing+0xd0/0x100 [26620.095954] ? _raw_spin_unlock_irqrestore+0x16/0x30 [26620.095955] ? i915_gem_execbuffer2_ioctl+0xc9/0x240 [i915] [26620.095977] ? __wake_up_sync_key+0x32/0x50 [26620.095979] ? i915_gem_execbuffer2_ioctl+0xc9/0x240 [i915] [26620.096001] ? __slab_alloc.isra.0+0x67/0xc0 [26620.096003] i915_gem_execbuffer2_ioctl+0x11a/0x240 [i915] Results from decode_stacktrace.sh pointed to dereference of a file pointer field of a i915 TTM page vector container associated with an object being purged on eviction. That path is taken when the object is marked as no longer needed. Code analysis revealed a possibility of the i915 TTM page vector container being replaced with a new instance inside a function that purges content of the object, should it be still busy. That function is called, indirectly via a more general function that changes the object's placement and caching policy, ---truncated---
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
- git.kernel.org/stable/c/073bcbc95e9648c976da1654c7590a8d6ee12c2d
- git.kernel.org/stable/c/28b22dbaf407598cb3bb1d2c586a6f8018690ac2
- git.kernel.org/stable/c/5c4063c87a619e4df954c179d24628636f5db15f
- git.kernel.org/stable/c/a29654d451bbffe63d584a4cf64ad0efce6bcf1c
- git.kernel.org/stable/c/c9ae7e7e3bc98615364313b08d7acea5239ded0b
- git.kernel.org/stable/c/df73f3bc731af1c39ac5405bc59c4e7c6f8e9117
Recent Use After Free vulnerabilities
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.8 High severity
- 9.8 Critical severity
- 8.8 High severity
Spotted an error? Tell us.