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

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-24 · updated 2026-06-17

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.

Affected products

Linux kernel: from 5.15 before 6.18.11; from 6.19 before 6.19.1 — fixed in 6.18.11, 6.19.1

How to fix

Upgrade to a fixed version: Linux kernel 6.18.11, 6.19.1. Check the vendor advisory for mitigations.

References

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