Linux: Use After Free
CVE-2026-53129 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 40148c615687c1692712e50a6de53d62dfbfc20f, cbdd6f0fb19a0ce8a013acd80ac87a62f57fa20d, a88d39a74a208e197c03bffaa2df34de732af19f 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 40148c615687c1692712e50a6de53d62dfbfc20f or cbdd6f0fb19a0ce8a013acd80ac87a62f57fa20d or a88d39a74a208e197c03bffaa2df34de732af19f or 0e4eff315d799f5842b95872199b0f0fb8ef5f51, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.91 or 6.18.33 or 7.0.10, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | c2f3140fe2eceb3a6c1615b2648b9471544881c6 up to, but not including, 40148c615687c1692712e50a6de53d62dfbfc20f; c2f3140fe2eceb3a6c1615b2648b9471544881c6 up to, but not including, cbdd6f0fb19a0ce8a013acd80ac87a62f57fa20d; c2f3140fe2eceb3a6c1615b2648b9471544881c6 up to, but not including, a88d39a74a208e197c03bffaa2df34de732af19f; c2f3140fe2eceb3a6c1615b2648b9471544881c6 up to, but not including, 0e4eff315d799f5842b95872199b0f0fb8ef5f51; c2f3140fe2eceb3a6c1615b2648b9471544881c6 up to, but not including, b25fd3523bef88fb7ffd4c5b63bbe9c08f73bb4c; c2f3140fe2eceb3a6c1615b2648b9471544881c6 up to, but not including, d227786ab1119669df4dc333a61510c52047cce4; 4.6 | 40148c615687c1692712e50a6de53d62dfbfc20f, cbdd6f0fb19a0ce8a013acd80ac87a62f57fa20d, a88d39a74a208e197c03bffaa2df34de732af19f, 0e4eff315d799f5842b95872199b0f0fb8ef5f51, b25fd3523bef88fb7ffd4c5b63bbe9c08f73bb4c, d227786ab1119669df4dc333a61510c52047cce4 |
| Linux | Linux Kernel | 4.6 up to, but not including, 6.12.91; 6.13 up to, but not including, 6.18.33; 6.19 up to, but not including, 7.0.10 | 6.12.91, 6.18.33, 7.0.10 |
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: fs/mbcache: cancel shrink work before destroying the cache mb_cache_destroy() calls shrinker_free() and then frees all cache entries and the cache itself, but it does not cancel the pending c_shrink_work work item first. If mb_cache_entry_create() schedules c_shrink_work via schedule_work() and the work item is still pending or running when mb_cache_destroy() runs, mb_cache_shrink_worker() will access the cache after its memory has been freed, causing a use-after-free. This is only reachable by a privileged user (root or CAP_SYS_ADMIN) who can trigger the last put of a mounted ext2/ext4/ocfs2 filesystem. Cancel the work item with cancel_work_sync() before calling shrinker_free(), ensuring the worker has finished and will not be rescheduled before the cache is torn down.
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
Other references
Recent Use After Free vulnerabilities
- 7.5 High severity
- 8.8 High severity
- 7.8 High severity
- 8.8 High severity
- 8.8 High severity
- 9.6 Critical severity
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