# CVE-2022-49562: KVM: x86: Use __try_cmpxchg_user() to update guest PTE A/D bits

> A flaw in Linux kernel KVM allows accessing random physical pages due to incorrect PTE handling, potentially leading to memory corruption and privilege escalation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/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:** 26 Feb 2025
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-68690, DEBIAN-CVE-2022-49562, GHSA-xpvw-h2w8-vrf9, ROOT-OS-DEBIAN-11-CVE-2022-49562, ROOT-OS-UBUNTU-2204-CVE-2022-49562, UBUNTU-CVE-2022-49562

## What is CVE-2022-49562?

CVE-2022-49562 is a high-severity memory corruption vulnerability in Linux kernel, published on 26 Feb 2025. 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: Use __try_cmpxchg_user() to update guest PTE A/D bits

Use the recently introduced __try_cmpxchg_user() to update guest PTE A/D
bits instead of mapping the PTE into kernel address space.  The VM_PFNMAP
path is broken as it assumes that vm_pgoff is the base pfn of the mapped
VMA range, which is conceptually wrong as vm_pgoff is the offset relative
to the file and has nothing to do with the pfn.  The horrific hack worked
for the original use case (backing guest memory with /dev/mem), but leads
to accessing "random" pfns for pretty much any other VM_PFNMAP case.

## Which versions are affected by CVE-2022-49562?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-49562?

Apply the vendor's patch.

## Is CVE-2022-49562 being exploited?

There is no known exploitation of CVE-2022-49562 in the wild and no public exploit code.

## 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-2022-49562 and fix it if it is affected.

What it is: CVE-2022-49562 is a high-severity memory corruption vulnerability in Linux kernel, published on 26 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2022-49562 in the wild and no public exploit code.

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-2022-49562/ (Markdown: https://insights.sbomify.com/CVE-2022-49562/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-49562
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-49562
- OSV: https://osv.dev/vulnerability/CVE-2022-49562

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-49562/
Summaries are generated and may contain mistakes; the official description above is the record.