Linux: Use After Free
CVE-2026-64300 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 c8b7e113f7b61eef2f017e6329c27c2331058c5a, 0cff05bd2186020f8706233e261016d149cc24db, 5948aaf64f81f217a25dcc2bf6c0779bca19566c 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 0.18% 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 c8b7e113f7b61eef2f017e6329c27c2331058c5a or 0cff05bd2186020f8706233e261016d149cc24db or 5948aaf64f81f217a25dcc2bf6c0779bca19566c, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.39 or 7.1.4, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | b709eb872e19a19607bbb6d2975bc264d59735cf up to, but not including, c8b7e113f7b61eef2f017e6329c27c2331058c5a; b709eb872e19a19607bbb6d2975bc264d59735cf up to, but not including, 0cff05bd2186020f8706233e261016d149cc24db; b709eb872e19a19607bbb6d2975bc264d59735cf up to, but not including, 5948aaf64f81f217a25dcc2bf6c0779bca19566c; 6.14 | c8b7e113f7b61eef2f017e6329c27c2331058c5a, 0cff05bd2186020f8706233e261016d149cc24db, 5948aaf64f81f217a25dcc2bf6c0779bca19566c |
| Linux | Linux Kernel | 6.14 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.4; 7.2 | 6.18.39, 7.1.4 |
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: perf/aux: Fix page UAF in map_range() map_range() reads rb->aux_pages[], rb->aux_nr_pages and rb->aux_pgoff via perf_mmap_to_page() while holding only event->mmap_mutex. Those fields are serialized by rb->aux_mutex, and mmap_mutex is per event. Thus, two events sharing one rb via PERF_EVENT_IOC_SET_OUTPUT can race rb_alloc_aux() with map_range(), leading to a page-UAF scenario as follows: CPU 0 CPU 1 ===== ===== rb_alloc_aux() map_range() [1]: allocate rb->aux_pages[0] [2]: rb->aux_nr_pages++ [3]: perf_mmap_to_page() returns rb->aux_pages[0] [4]: map it as VM_PFNMAP [5]: rb->aux_pgoff = 1 munmap the page [6]: free rb->aux_pages[0] Pages mapped as VM_PFNMAP have no refcount protection, so CPU 1 holds a mapping to a freed physical frame. Fix this by taking rb->aux_mutex across the page walk in map_range().
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
- 9.8 Critical severity
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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