Linux: Use After Free
CVE-2026-31554 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 027145ace09fad4c7cbcd6c61fe9b429c63eb0e5, 18b7d09c2b794c71d4252f3ea2cf84ad12b73d6a, e2f78c7ec1655fedd945366151ba54fcb9580508 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 0.21% 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 027145ace09fad4c7cbcd6c61fe9b429c63eb0e5 or 18b7d09c2b794c71d4252f3ea2cf84ad12b73d6a or e2f78c7ec1655fedd945366151ba54fcb9580508 or 19f94b39058681dec64a10ebeb6f23fe7fc3f77a, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.80 or 6.18.21 or 6.19.11, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 0f4b5f972216782a4acb1ae00dcb55173847c2ff up to, but not including, 027145ace09fad4c7cbcd6c61fe9b429c63eb0e5; 0f4b5f972216782a4acb1ae00dcb55173847c2ff up to, but not including, 18b7d09c2b794c71d4252f3ea2cf84ad12b73d6a; 0f4b5f972216782a4acb1ae00dcb55173847c2ff up to, but not including, e2f78c7ec1655fedd945366151ba54fcb9580508; 0f4b5f972216782a4acb1ae00dcb55173847c2ff up to, but not including, 19f94b39058681dec64a10ebeb6f23fe7fc3f77a; 6.7 | 027145ace09fad4c7cbcd6c61fe9b429c63eb0e5, 18b7d09c2b794c71d4252f3ea2cf84ad12b73d6a, e2f78c7ec1655fedd945366151ba54fcb9580508, 19f94b39058681dec64a10ebeb6f23fe7fc3f77a |
| Linux | Linux Kernel | 6.7.1 up to, but not including, 6.12.80; 6.13 up to, but not including, 6.18.21; 6.19 up to, but not including, 6.19.11; 6.7; 7.0 | 6.12.80, 6.18.21, 6.19.11 |
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: futex: Require sys_futex_requeue() to have identical flags Nicholas reported that his LLM found it was possible to create a UaF when sys_futex_requeue() is used with different flags. The initial motivation for allowing different flags was the variable sized futex, but since that hasn't been merged (yet), simply mandate the flags are identical, as is the case for the old style sys_futex() requeue operations.
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
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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