Linux: Use After Free
CVE-2026-46317 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 8.8 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 918450ad6010df6ecd2efde12a1409e011da22d6, 4424dbcb06d68e34e51c019a5781a7dc00731971, 70543358fa08e0f7cebc3447c3b70fe97ad7aaa8 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 0.13% 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 918450ad6010df6ecd2efde12a1409e011da22d6 or 4424dbcb06d68e34e51c019a5781a7dc00731971 or 70543358fa08e0f7cebc3447c3b70fe97ad7aaa8, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.35 or 7.0.12, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 4f128f8e1aaac189f83d0f828bcdb2986d8d2e51 up to, but not including, 918450ad6010df6ecd2efde12a1409e011da22d6; 4f128f8e1aaac189f83d0f828bcdb2986d8d2e51 up to, but not including, 4424dbcb06d68e34e51c019a5781a7dc00731971; 4f128f8e1aaac189f83d0f828bcdb2986d8d2e51 up to, but not including, 70543358fa08e0f7cebc3447c3b70fe97ad7aaa8; 6.11 | 918450ad6010df6ecd2efde12a1409e011da22d6, 4424dbcb06d68e34e51c019a5781a7dc00731971, 70543358fa08e0f7cebc3447c3b70fe97ad7aaa8 |
| Linux | Linux Kernel | 6.11 up to, but not including, 6.18.35; 6.19 up to, but not including, 7.0.12; 7.1 | 6.18.35, 7.0.12 |
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
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- 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:C/C:H/I:H/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Reassign nested_mmus array behind mmu_lock kvm->arch.nested_mmus[] is walked under kvm->mmu_lock, including from the MMU notifier path (kvm_unmap_gfn_range() -> kvm_nested_s2_unmap()), which can run at any time. kvm_vcpu_init_nested() reallocates the array and frees the old buffer while holding only kvm->arch.config_lock, so such a walker can reference the freed array. Allocate the new array outside of mmu_lock, as the allocation can sleep. Under the lock, copy the existing entries, fix up the back pointers and reassign the array. Free the old buffer after dropping the lock, as kvfree() can sleep as well.
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
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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