Linux: Use After Free
CVE-2026-64251 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 ba0b9f04c7a5f9887b8ce672eaf049502c0548ec, e91df6d273445c03f5aa302bfe147eda33d45794, 73569a44fca2992f0ca4a4c0104069741b9873a0 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 0.17% 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 ba0b9f04c7a5f9887b8ce672eaf049502c0548ec or e91df6d273445c03f5aa302bfe147eda33d45794 or 73569a44fca2992f0ca4a4c0104069741b9873a0 or 257595adf9dac15ae1edd9d07753fbc576a7583d, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.95 or 6.18.38 or 7.1.3, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 249ebf3f65f8530beb2cbfb91bff1d83ba88d23c up to, but not including, ba0b9f04c7a5f9887b8ce672eaf049502c0548ec; 249ebf3f65f8530beb2cbfb91bff1d83ba88d23c up to, but not including, e91df6d273445c03f5aa302bfe147eda33d45794; 249ebf3f65f8530beb2cbfb91bff1d83ba88d23c up to, but not including, 73569a44fca2992f0ca4a4c0104069741b9873a0; 249ebf3f65f8530beb2cbfb91bff1d83ba88d23c up to, but not including, 257595adf9dac15ae1edd9d07753fbc576a7583d; 6.11 | ba0b9f04c7a5f9887b8ce672eaf049502c0548ec, e91df6d273445c03f5aa302bfe147eda33d45794, 73569a44fca2992f0ca4a4c0104069741b9873a0, 257595adf9dac15ae1edd9d07753fbc576a7583d |
| Linux | Linux Kernel | 6.11 up to, but not including, 6.12.95; 6.13 up to, but not including, 6.18.38; 6.19 up to, but not including, 7.1.3 | 6.12.95, 6.18.38, 7.1.3 |
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: pwrseq: core: fix use-after-free in pwrseq_debugfs_seq_next() pwrseq_debugfs_seq_next() declares 'next' with __free(put_device), which causes put_device() to be called on the returned pointer when the variable goes out of scope. This results in a use-after-free since the seq_file framework receives a pointer whose reference has already been dropped. Simply removing __free(put_device) would fix the UAF but would leak the reference acquired by bus_find_next_device(), as stop() only calls up_read(&pwrseq_sem) and never releases the device reference. Fix this by making the reference counting consistent across all seq_file callbacks, matching the standard pattern used by PCI and SCSI: - start(): use get_device() so it returns a referenced pointer. - next(): explicitly put_device(curr) to release the previous device's reference (no NULL check needed - the seq_file framework only calls next() while the previous return was non-NULL). - stop(): put_device(data) to release the last iterated device's reference, with a NULL guard since stop() may be called with NULL when start() returned NULL or next() reached end-of-sequence.
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
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
Spotted an error? Tell us.