# CVE-2026-80724: ptp: vmclock: prevent read-only mappings from becoming writable

> A guest user can escalate privileges by modifying read-only vmclock data via mprotect, requiring kernel patching.

- **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:** 28 Aug 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-80724, DEBIAN-CVE-2026-80724, GHSA-66mv-wq2c-77c3, UBUNTU-CVE-2026-80724, openSUSE-SU-2026:11703-1

## What is CVE-2026-80724?

CVE-2026-80724 is a high-severity vulnerability in Linux, published on 28 Aug 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:

ptp: vmclock: prevent read-only mappings from becoming writable

vmclock_miscdev_mmap() rejects writable mappings of the shared vmclock
ABI page with -EROFS, but leaves VM_MAYWRITE set.  Userspace can map the
page read-only and then upgrade it to writable with mprotect(), after
which the guest can corrupt the host-written timekeeping data (sequence
counter, UTC time, TSC offset) that the vmclock ABI defines as read-only.

Clear VM_MAYWRITE on the read-only path so the mapping cannot be
upgraded, as i915 does for its read-only objects and as fixed in drm/vc4
(CVE-2026-68445) and drm/panthor (CVE-2024-53071).

## Which versions are affected by CVE-2026-80724?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kernel-source` | openSUSE:Tumbleweed | All versions | 7.2.3-1.1 |

## How do I fix CVE-2026-80724?

Apply the vendor's patch.

## Is CVE-2026-80724 being exploited?

There is no known exploitation of CVE-2026-80724 in the wild and no public exploit code.

Public exploit code:

- CVE-2026-80724 PoC + full write-up — Linux kernel ptp/vmclock read-only mapping becomes writable (VM_MAYWRITE). Discovered, reported & fixed by Abdifatah Suruur (suruurism) (github_poc): https://github.com/suruurism/cve-writeups-and-pocs

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80724 and fix it if it is affected.

What it is: CVE-2026-80724 is a high-severity vulnerability in Linux, published on 28 Aug 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-2026-80724 in the wild and no public exploit code.

Affected product: Linux. 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-2026-80724/ (Markdown: https://insights.sbomify.com/CVE-2026-80724/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80724
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80724
- OSV: https://osv.dev/vulnerability/CVE-2026-80724

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80724/
Summaries are generated and may contain mistakes; the official description above is the record.