Linux: Use After Free
CVE-2026-31455 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 e6cc490048f78b009259a5f032acead9f789c34c, 239d734c00644072862fa833805c4471573b1445, bda27fc0b4eb3a425d9a18475c4cb94fbe862c60 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 e6cc490048f78b009259a5f032acead9f789c34c or 239d734c00644072862fa833805c4471573b1445 or bda27fc0b4eb3a425d9a18475c4cb94fbe862c60 or d38135af04a3ad8a585c899d176efc8e97853115, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.168 or 6.6.131, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 90c60e16401248a4900f3f9387f563d0178dcf34 up to, but not including, e6cc490048f78b009259a5f032acead9f789c34c; 90c60e16401248a4900f3f9387f563d0178dcf34 up to, but not including, 239d734c00644072862fa833805c4471573b1445; 90c60e16401248a4900f3f9387f563d0178dcf34 up to, but not including, bda27fc0b4eb3a425d9a18475c4cb94fbe862c60; 90c60e16401248a4900f3f9387f563d0178dcf34 up to, but not including, d38135af04a3ad8a585c899d176efc8e97853115; 90c60e16401248a4900f3f9387f563d0178dcf34 up to, but not including, a89434a6188d8430ea31120da96e3e4cefb58686; 90c60e16401248a4900f3f9387f563d0178dcf34 up to, but not including, 8147e304d7d32fd5c3e943babc296ce2873dc279; 90c60e16401248a4900f3f9387f563d0178dcf34 up to, but not including, 558e3275d8a3b101be18a7fe7d1634053e9d9b07; 90c60e16401248a4900f3f9387f563d0178dcf34 up to, but not including, 4f24a767e3d64a5f58c595b5c29b6063a201f1e3; and 1 more ranges | e6cc490048f78b009259a5f032acead9f789c34c, 239d734c00644072862fa833805c4471573b1445, bda27fc0b4eb3a425d9a18475c4cb94fbe862c60, d38135af04a3ad8a585c899d176efc8e97853115, a89434a6188d8430ea31120da96e3e4cefb58686, 8147e304d7d32fd5c3e943babc296ce2873dc279 |
| Linux | Linux Kernel | 5.9 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.168; 6.2 up to, but not including, 6.6.131; 6.7 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; 7.0 | 5.10.253, 5.15.203, 6.1.168, 6.6.131, 6.12.80, 6.18.21 |
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: xfs: stop reclaim before pushing AIL during unmount The unmount sequence in xfs_unmount_flush_inodes() pushed the AIL while background reclaim and inodegc are still running. This is broken independently of any use-after-free issues - background reclaim and inodegc should not be running while the AIL is being pushed during unmount, as inodegc can dirty and insert inodes into the AIL during the flush, and background reclaim can race to abort and free dirty inodes. Reorder xfs_unmount_flush_inodes() to stop inodegc and cancel background reclaim before pushing the AIL. Stop inodegc before cancelling m_reclaim_work because the inodegc worker can re-queue m_reclaim_work via xfs_inodegc_set_reclaimable.
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: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/239d734c00644072862fa833805c4471573b1445
- git.kernel.org/stable/c/4f24a767e3d64a5f58c595b5c29b6063a201f1e3
- git.kernel.org/stable/c/558e3275d8a3b101be18a7fe7d1634053e9d9b07
- git.kernel.org/stable/c/8147e304d7d32fd5c3e943babc296ce2873dc279
- git.kernel.org/stable/c/a89434a6188d8430ea31120da96e3e4cefb58686
- git.kernel.org/stable/c/bda27fc0b4eb3a425d9a18475c4cb94fbe862c60
- git.kernel.org/stable/c/d38135af04a3ad8a585c899d176efc8e97853115
- git.kernel.org/stable/c/e6cc490048f78b009259a5f032acead9f789c34c
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 7.8 High severity
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