# CVE-2026-31537: smb: server: make use of smbdirect_socket.send_io.bcredits

CVE-2026-31537 is fixed in linux on 1 platform by DEBIAN-CVE-2026-31537 (version 6.18.12-1), released May 15, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-31537
- Priority: High
- CVSS: 7.1 (Important)
- EPSS: 0.0012
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 24, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-31537

## Description

In the Linux kernel, the following vulnerability has been resolved:  smb: server: make use of smbdirect_socket.send_io.bcredits  It turns out that our code will corrupt the stream of reassabled data transfer messages when we trigger an immendiate (empty) send.  In order to fix this we'll have a single 'batch' credit per connection. And code getting that credit is free to use as much messages until remaining_length reaches 0, then the batch credit it given back and the next logical send can happen.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 6.18.12-1 | [DEBIAN-CVE-2026-31537](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31537.md) | May 15, 2026 |

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Data as of 2026-11-09T07:25:28Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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