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

What is CVE-2026-31537?

CVE-2026-31537 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official 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.

Which versions are affected by CVE-2026-31537?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-31537?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-31537 being exploited?

There is no known exploitation of CVE-2026-31537 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-31537, DEBIAN-CVE-2026-31537, GHSA-2996-rjmh-m244, ROOT-OS-DEBIAN-12-CVE-2026-31537, ROOT-OS-DEBIAN-13-CVE-2026-31537, ROOT-OS-UBUNTU-2204-CVE-2026-31537 and 2 more.