Linux: Use After Free
CVE-2026-64075 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 56b4cfcf1518245493c60fd39c56978f508f1816, a4f6a9005ed6cfd360ef2520430927f05f92ffb0, 657b594b2084b39a4bc6d8493aa2140cb00cea49 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 56b4cfcf1518245493c60fd39c56978f508f1816 or a4f6a9005ed6cfd360ef2520430927f05f92ffb0 or 657b594b2084b39a4bc6d8493aa2140cb00cea49, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.34 or 7.0.11, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 4346ba1604093305a287e08eb465a9c15ba05b80 up to, but not including, 56b4cfcf1518245493c60fd39c56978f508f1816; 4346ba1604093305a287e08eb465a9c15ba05b80 up to, but not including, a4f6a9005ed6cfd360ef2520430927f05f92ffb0; 4346ba1604093305a287e08eb465a9c15ba05b80 up to, but not including, 657b594b2084b39a4bc6d8493aa2140cb00cea49; 6.14 | 56b4cfcf1518245493c60fd39c56978f508f1816, a4f6a9005ed6cfd360ef2520430927f05f92ffb0, 657b594b2084b39a4bc6d8493aa2140cb00cea49 |
| Linux | Linux Kernel | 6.14 up to, but not including, 6.18.34; 6.19 up to, but not including, 7.0.11; 7.1 | 6.18.34, 7.0.11 |
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: fprobe: Fix unregister_fprobe() to wait for RCU grace period Commit 4346ba1604093 ("fprobe: Rewrite fprobe on function-graph tracer") changed fprobe to register struct fprobe to an rcu-hlist, but it forgot to wait for RCU GP. Thus there can be use-after-free if the fprobe is released right after unregistering. This can be happened on fprobe event and sample module code. To fix this issue, add synchronize_rcu() in unregister_fprobe(). Note that BPF is OK because fprobe is used as a part of bpf_kprobe_multi_link. This unregisters its fprobe in bpf_kprobe_multi_link_release() and it is deallocated via bpf_kprobe_multi_link_dealloc(), which is invoked from bpf_link_defer_dealloc_rcu_gp() RCU callback. For BPF, this also introduced unregister_fprobe_async() which does NOT wait for RCU grace priod.
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
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.8 High severity
- 9.8 Critical severity
- 8.8 High severity
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