# CVE-2026-89632: smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()

CVE-2026-89632 is fixed in linux on 1 platform by DEBIAN-CVE-2026-89632 (version 7.2.6-1), released September 11, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-89632
- Priority: High
- CVSS: 8.2 (Moderate)
- EPSS: 0.0055
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 11, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-89632

## Description

In the Linux kernel, the following vulnerability has been resolved:  smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()  reparse_buf_ptr() reads buf->ReparseDataLength before checking that count covers the full fixed header:      buf = (struct reparse_data_buffer *)((u8 *)io + off);     len = sizeof(*buf);                          /* 8 bytes */     rdlen = le16_to_cpu(buf->ReparseDataLength); /* offset 4, 2 bytes */      if (count < len || count < rdlen + len)      /* check comes after */  struct reparse_data_buffer has ReparseDataLength at offset 4.  If a server returns OutputCount < 6, the read at offset 4-5 reaches past the end of the received data.  The off+count bounds against iov_len were already validated, but that does not protect against count being smaller than sizeof(*buf).  Split the check: verify count >= sizeof(*buf) before reading ReparseDataLength, then verify count covers the data region.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-89632](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89632.md) | Sep 11, 2026 |

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Data as of 2026-11-08T06:59:42Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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