# CVE-2023-52633: um: time-travel: fix time corruption

> A race condition in Linux kernel time-travel mode can cause a crash when timer interrupts occur during time adjustment, leading to denial of service.

- **Severity:** Medium 5.0 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:R/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:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 2 Apr 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-52633, DEBIAN-CVE-2023-52633, GHSA-c7h5-f667-cvc5, ROOT-OS-DEBIAN-11-CVE-2023-52633, UBUNTU-CVE-2023-52633

## What is CVE-2023-52633?

CVE-2023-52633 is a medium-severity vulnerability in Linux kernel, published on 2 Apr 2024. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

um: time-travel: fix time corruption

In 'basic' time-travel mode (without =inf-cpu or =ext), we
still get timer interrupts. These can happen at arbitrary
points in time, i.e. while in timer_read(), which pushes
time forward just a little bit. Then, if we happen to get
the interrupt after calculating the new time to push to,
but before actually finishing that, the interrupt will set
the time to a value that's incompatible with the forward,
and we'll crash because time goes backwards when we do the
forwarding.

Fix this by reading the time_travel_time, calculating the
adjustment, and doing the adjustment all with interrupts
disabled.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2023-52633?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-52633?

Apply the vendor's patch.

## Is CVE-2023-52633 being exploited?

There is no known exploitation of CVE-2023-52633 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-2023-52633 and fix it if it is affected.

What it is: CVE-2023-52633 is a medium-severity vulnerability in Linux kernel, published on 2 Apr 2024. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2023-52633 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-2023-52633/ (Markdown: https://insights.sbomify.com/CVE-2023-52633/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-52633
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-52633
- OSV: https://osv.dev/vulnerability/CVE-2023-52633

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-52633/
Summaries are generated and may contain mistakes; the official description above is the record.