CyberSecBulletin
CVE-2026-53359NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-53359 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 0b5e8ead71e683bcf6232db16234cf7e6d553a23, b1337aae5e194324e4810d561764e7793f8b3864, 9291654d69e08542de37755cebe4d5b02c3170d1 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 1.37% chance of exploitation within 30 days, higher than 72% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 0b5e8ead71e683bcf6232db16234cf7e6d553a23 or b1337aae5e194324e4810d561764e7793f8b3864 or 9291654d69e08542de37755cebe4d5b02c3170d1 or 2ad3afa40ac6aa340dada122f9abfa46c0a6eb35, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.1.177 or 6.6.144 or 6.12.95 or 6.18.38, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux2032a93d66fa282ba0f2ea9152eeff9511fa9a96 up to, but not including, 0b5e8ead71e683bcf6232db16234cf7e6d553a23; 2032a93d66fa282ba0f2ea9152eeff9511fa9a96 up to, but not including, b1337aae5e194324e4810d561764e7793f8b3864; 2032a93d66fa282ba0f2ea9152eeff9511fa9a96 up to, but not including, 9291654d69e08542de37755cebe4d5b02c3170d1; 2032a93d66fa282ba0f2ea9152eeff9511fa9a96 up to, but not including, 2ad3afa40ac6aa340dada122f9abfa46c0a6eb35; 2032a93d66fa282ba0f2ea9152eeff9511fa9a96 up to, but not including, 5e470998a23e4c3d89ed24e8172cb22747e61efa; 2032a93d66fa282ba0f2ea9152eeff9511fa9a96 up to, but not including, 1ae7d5a6db6c190ce183e3098ca0e0846e14d462; 2032a93d66fa282ba0f2ea9152eeff9511fa9a96 up to, but not including, 81ccda30b4e83d8f5cc4fd50503c44e3a33abfeb; 2.6.360b5e8ead71e683bcf6232db16234cf7e6d553a23, b1337aae5e194324e4810d561764e7793f8b3864, 9291654d69e08542de37755cebe4d5b02c3170d1, 2ad3afa40ac6aa340dada122f9abfa46c0a6eb35, 5e470998a23e4c3d89ed24e8172cb22747e61efa, 1ae7d5a6db6c190ce183e3098ca0e0846e14d462
LinuxLinux Kernel2.6.36 up to, but not including, 6.1.177; 6.2 up to, but not including, 6.6.144; 6.7 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, 7.1.36.1.177, 6.6.144, 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
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: x86: Fix shadow paging use-after-free due to unexpected role Commit 0cb2af2ea66ad ("KVM: x86: Fix shadow paging use-after-free due to unexpected GFN") fixed a shadow paging mismatch between stored and computed GFNs; the bug could be triggered by changing a PDE mapping from outside the guest, and then deleting a memslot. The rmap_remove() call would miss entries created after the PDE change because the GFN of the leaf SPTE does not match the GFN of the struct kvm_mmu_page. A similar hole however remains if the modified PDE points to a non-leaf page. In this case the gfn can be made to match, but the role does not match: the original large 2MB page creates a kvm_mmu_page with direct=1, while the new 4KB needs a kvm_mmu_page with direct=0. However, kvm_mmu_get_child_sp() does not compare the role, and therefore reuses the page. The next step is installing a leaf (4KB) SPTE on the new path which records an rmap entry under the gfn resolved by the walk. But when that child is zapped its parent kvm_mmu_page has direct=1 and kvm_mmu_page_get_gfn() computes the gfn for the 4KB page as sp->gfn + index instead of using sp->shadowed_translation[] (or sp->gfns[] in older kernels). It therefore fails to remove the recorded entry. When the memslot is dropped the shadow page is freed but the rmap entry survives, as in the scenario that was already fixed. Code that later walks that gfn (dirty logging, MMU notifier invalidation, and so on) dereferences an sptep that lies in the freed page, causing the use-after-free.

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.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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