Linux: Use After Free
CVE-2026-31644 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 691082c0b93c13a5e068c0905f673060bddc204e, 92a673019943770930e2a8bfd52e1aad47a1fc1f, 9950e9199b3dfdfbde0b8d96ba947d7b11243801 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 0.13% 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 691082c0b93c13a5e068c0905f673060bddc204e or 92a673019943770930e2a8bfd52e1aad47a1fc1f or 9950e9199b3dfdfbde0b8d96ba947d7b11243801 or 59c3d55a946cacdb4181600723c20ac4f4c20c84, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.82 or 6.18.23 or 6.19.13, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 89ba464fcf548d64bc7215dfe769f791330ae8b6 up to, but not including, 691082c0b93c13a5e068c0905f673060bddc204e; 89ba464fcf548d64bc7215dfe769f791330ae8b6 up to, but not including, 92a673019943770930e2a8bfd52e1aad47a1fc1f; 89ba464fcf548d64bc7215dfe769f791330ae8b6 up to, but not including, 9950e9199b3dfdfbde0b8d96ba947d7b11243801; 89ba464fcf548d64bc7215dfe769f791330ae8b6 up to, but not including, 59c3d55a946cacdb4181600723c20ac4f4c20c84; 6.12 | 691082c0b93c13a5e068c0905f673060bddc204e, 92a673019943770930e2a8bfd52e1aad47a1fc1f, 9950e9199b3dfdfbde0b8d96ba947d7b11243801, 59c3d55a946cacdb4181600723c20ac4f4c20c84 |
| Linux | Linux Kernel | 6.12.1 up to, but not including, 6.12.82; 6.13 up to, but not including, 6.18.23; 6.19 up to, but not including, 6.19.13; 6.12; 7.0 | 6.12.82, 6.18.23, 6.19.13 |
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: net: lan966x: fix use-after-free and leak in lan966x_fdma_reload() When lan966x_fdma_reload() fails to allocate new RX buffers, the restore path restarts DMA using old descriptors whose pages were already freed via lan966x_fdma_rx_free_pages(). Since page_pool_put_full_page() can release pages back to the buddy allocator, the hardware may DMA into memory now owned by other kernel subsystems. Additionally, on the restore path, the newly created page pool (if allocation partially succeeded) is overwritten without being destroyed, leaking it. Fix both issues by deferring the release of old pages until after the new allocation succeeds. Save the old page array before the allocation so old pages can be freed on the success path. On the failure path, the old descriptors, pages and page pool are all still valid, making the restore safe. Also ensure the restore path re-enables NAPI and wakes the netdev, matching the success path.
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
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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