Linux: Use After Free
CVE-2026-52971 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 95e8ae9af2a61b4e72f5c585bf4c7d8aaf2a2c98, ca9ed40f28949353911dcb524ff8fff2f3409c97, e42c755582f0960e684298762f0ab927b3778376 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 0.1% 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 95e8ae9af2a61b4e72f5c585bf4c7d8aaf2a2c98 or ca9ed40f28949353911dcb524ff8fff2f3409c97 or e42c755582f0960e684298762f0ab927b3778376, whichever matches your release line, or a later version.
- Update Linux Kernel to 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 | e0ea34158ee8c4f7536cd781010339ff28c0d24c up to, but not including, 95e8ae9af2a61b4e72f5c585bf4c7d8aaf2a2c98; e0ea34158ee8c4f7536cd781010339ff28c0d24c up to, but not including, ca9ed40f28949353911dcb524ff8fff2f3409c97; e0ea34158ee8c4f7536cd781010339ff28c0d24c up to, but not including, e42c755582f0960e684298762f0ab927b3778376; 6.17 | 95e8ae9af2a61b4e72f5c585bf4c7d8aaf2a2c98, ca9ed40f28949353911dcb524ff8fff2f3409c97, e42c755582f0960e684298762f0ab927b3778376 |
| Linux | Linux Kernel | 6.17 up to, but not including, 6.18.33; 6.19 up to, but not including, 7.0.10; 7.1 | 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 CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: net: ena: PHC: Fix potential use-after-free in get_timestamp Move the phc->active check and resp pointer assignment to after acquiring the spinlock. Previously, phc->active was checked without holding the lock, and resp was cached from ena_dev->phc.virt_addr before the lock was acquired. If ena_com_phc_destroy() runs between the lockless active check and the lock acquisition, it sets active=false, releases the lock, frees the DMA memory, and sets virt_addr=NULL. The get_timestamp path would then read a NULL virt_addr and dereference it. With both the active check and the pointer read under the lock, destroy cannot free the memory while get_timestamp is using it.
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
- 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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