# CVE-2026-31433: ksmbd: fix potencial OOB in get_file_all_info() for compound requests

CVE-2026-31433 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-31433, released May 15, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-31433
- Priority: High
- CVSS: 8.8 (Important)
- EPSS: 0.0060
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 22, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-31433

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.170-1 | [DEBIAN-CVE-2026-31433](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31433.md) | May 15, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.85-1 | [DEBIAN-CVE-2026-31433](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31433.md) | May 15, 2026 |
| Linux | linux Debian 14 | 6.19.11-1 | [DEBIAN-CVE-2026-31433](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31433.md) | May 15, 2026 |

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Data as of 2026-11-07T18:46:35Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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