# CVE-2026-23215: x86/vmware: Fix hypercall clobbers

> A kernel panic occurs in the Linux kernel's VMware mouse driver due to register clobbering, causing a denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 18 Feb 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-23215, DEBIAN-CVE-2026-23215, GHSA-g5pw-hppv-79r6, ROOT-OS-DEBIAN-11-CVE-2026-23215, ROOT-OS-DEBIAN-12-CVE-2026-23215, ROOT-OS-UBUNTU-2204-CVE-2026-23215, ROOT-OS-UBUNTU-2404-CVE-2026-23215, UBUNTU-CVE-2026-23215

## What is CVE-2026-23215?

CVE-2026-23215 is a medium-severity vulnerability in Linux kernel, published on 18 Feb 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:

x86/vmware: Fix hypercall clobbers

Fedora QA reported the following panic:

  BUG: unable to handle page fault for address: 0000000040003e54
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20251119-3.fc43 11/19/2025
  RIP: 0010:vmware_hypercall4.constprop.0+0x52/0x90
  ..
  Call Trace:
   vmmouse_report_events+0x13e/0x1b0
   psmouse_handle_byte+0x15/0x60
   ps2_interrupt+0x8a/0xd0
   ...

because the QEMU VMware mouse emulation is buggy, and clears the top 32
bits of %rdi that the kernel kept a pointer in.

The QEMU vmmouse driver saves and restores the register state in a
"uint32_t data[6];" and as a result restores the state with the high
bits all cleared.

RDI originally contained the value of a valid kernel stack address
(0xff5eeb3240003e54).  After the vmware hypercall it now contains
0x40003e54, and we get a page fault as a result when it is dereferenced.

The proper fix would be in QEMU, but this works around the issue in the
kernel to keep old setups working, when old kernels had not happened to
keep any state in %rdi over the hypercall.

In theory this same issue exists for all the hypercalls in the vmmouse
driver; in practice it has only been seen with vmware_hypercall3() and
vmware_hypercall4().  For now, just mark RDI/RSI as clobbered for those
two calls.  This should have a minimal effect on code generation overall
as it should be rare for the compiler to want to make RDI/RSI live
across hypercalls.

## Which versions are affected by CVE-2026-23215?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23215?

Apply the vendor's patch.

## Is CVE-2026-23215 being exploited?

There is no known exploitation of CVE-2026-23215 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-2026-23215 and fix it if it is affected.

What it is: CVE-2026-23215 is a medium-severity vulnerability in Linux kernel, published on 18 Feb 2026. 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-2026-23215 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-2026-23215/ (Markdown: https://insights.sbomify.com/CVE-2026-23215/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23215
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23215
- OSV: https://osv.dev/vulnerability/CVE-2026-23215

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23215/
Summaries are generated and may contain mistakes; the official description above is the record.