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

> A use-after-free in Linux KVM shadow paging allows local attackers to execute arbitrary code or escalate privileges via crafted memory slot operations.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Jul 2026
- **Updated:** 3 Oct 2026
- **Also known as:** BELL-CVE-2026-53359, DEBIAN-CVE-2026-53359, GHSA-wpw8-53h7-xqcq, RHSA-2026:43847, RHSA-2026:44003, RHSA-2026:44004, ROOT-OS-DEBIAN-11-CVE-2026-53359, ROOT-OS-DEBIAN-12-CVE-2026-53359, ROOT-OS-UBUNTU-2204-CVE-2026-53359, ROOT-OS-UBUNTU-2404-CVE-2026-53359, SUSE-SU-2026:3376-1, UBUNTU-CVE-2026-53359

## What is CVE-2026-53359?

CVE-2026-53359 is a high-severity use after free vulnerability in Linux kernel, published on 4 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### 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.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-53359?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kpatch-patch-4_18_0-553_109_1` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-7.el8_10 |
| `kpatch-patch-4_18_0-553_109_1-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-7.el8_10 |
| `kpatch-patch-4_18_0-553_109_1-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-7.el8_10 |
| `kpatch-patch-4_18_0-553_125_1` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-4.el8_10 |
| `kpatch-patch-4_18_0-553_125_1-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-4.el8_10 |
| `kpatch-patch-4_18_0-553_125_1-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-4.el8_10 |
| `kpatch-patch-4_18_0-553_53_1` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-14.el8_10 |
| `kpatch-patch-4_18_0-553_53_1-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-14.el8_10 |
| `kpatch-patch-4_18_0-553_53_1-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-14.el8_10 |
| `kpatch-patch-4_18_0-553_72_1` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-11.el8_10 |
| `kpatch-patch-4_18_0-553_72_1-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-11.el8_10 |
| `kpatch-patch-4_18_0-553_72_1-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-11.el8_10 |
| `kpatch-patch-4_18_0-553_85_1` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-9.el8_10 |
| `kpatch-patch-4_18_0-553_85_1-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-9.el8_10 |
| `kpatch-patch-4_18_0-553_85_1-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-9.el8_10 |
| `kpatch-patch-4_18_0-477_107_1` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-10.el8_8 |
| `kpatch-patch-4_18_0-477_107_1-debuginfo` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-10.el8_8 |
| `kpatch-patch-4_18_0-477_107_1-debugsource` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-10.el8_8 |
| `kpatch-patch-4_18_0-477_120_1` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-9.el8_8 |
| `kpatch-patch-4_18_0-477_120_1-debuginfo` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-9.el8_8 |
| `kpatch-patch-4_18_0-477_120_1-debugsource` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-9.el8_8 |
| `kpatch-patch-4_18_0-477_130_1` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-7.el8_8 |
| `kpatch-patch-4_18_0-477_130_1-debuginfo` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-7.el8_8 |
| `kpatch-patch-4_18_0-477_130_1-debugsource` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-7.el8_8 |
| `kpatch-patch-4_18_0-477_143_1` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-3.el8_8 |
| `kpatch-patch-4_18_0-477_143_1-debuginfo` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-3.el8_8 |
| `kpatch-patch-4_18_0-477_143_1-debugsource` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-3.el8_8 |
| `kpatch-patch-4_18_0-477_97_1` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-14.el8_8 |
| `kpatch-patch-4_18_0-477_97_1-debuginfo` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-14.el8_8 |
| `kpatch-patch-4_18_0-477_97_1-debugsource` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:1-14.el8_8 |
| `kpatch-patch-5_14_0-284_117_1` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-17.el9_2 |
| `kpatch-patch-5_14_0-284_117_1-debuginfo` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-17.el9_2 |
| `kpatch-patch-5_14_0-284_117_1-debugsource` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-17.el9_2 |
| `kpatch-patch-5_14_0-284_134_1` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-11.el9_2 |
| `kpatch-patch-5_14_0-284_134_1-debuginfo` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-11.el9_2 |
| `kpatch-patch-5_14_0-284_134_1-debugsource` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-11.el9_2 |
| `kpatch-patch-5_14_0-284_148_1` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-9.el9_2 |
| `kpatch-patch-5_14_0-284_148_1-debuginfo` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-9.el9_2 |
| `kpatch-patch-5_14_0-284_148_1-debugsource` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-9.el9_2 |
| `kpatch-patch-5_14_0-284_158_1` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-7.el9_2 |

Products: Linux kernel.

## How do I fix CVE-2026-53359?

Apply the vendor's patch.

## Is CVE-2026-53359 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53359 exists.

Public exploit code:

- Complete fix collection for the CVE-2026-53359 guest-to-host escape vulnerability in the KVM/x86 shadow MMU. From zero-downtime livepatch to kernel upgrade — covers every operational scenario. / KVM/x86 shadow MMU 虚拟机逃逸漏洞（CVE-2026-53359）的完整修复方案集合。 从零停机热修复到内核升级，覆盖所有运维场景。 (github_poc): https://github.com/Aoripus-LTD/Januscape-Hotfix
- CVE-2026-53359 (github_poc): https://github.com/0xredash/CVE-2026-53359
- Linux 内核升级指南 - 修复 CVE-2026-53359 (github_poc): https://github.com/chuzhongyun/CVE-2026-53359-Kernel-Fix
- CVE-2026-53359漏洞补丁 (github_poc): https://github.com/xj2268-TA/KVM-Januscape
- CVE-2026-53359 - Draft (github_poc): https://github.com/HORKimhab/CVE-2026-53359
- Tracking Januscape (CVE-2026-53359), the KVM/x86 guest-to-host escape (github_poc): https://github.com/suominen/januscape

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53359 and fix it if it is affected.

What it is: CVE-2026-53359 is a high-severity use after free vulnerability in Linux kernel, published on 4 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53359 exists.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-53359/ (Markdown: https://insights.sbomify.com/CVE-2026-53359/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53359
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53359
- OSV: https://osv.dev/vulnerability/CVE-2026-53359

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53359/
Summaries are generated and may contain mistakes; the official description above is the record.