CVE-2026-31608 smb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list()

What is CVE-2026-31608?

CVE-2026-31608 is a critical use after free vulnerability in Linux kernel, published on 24 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

smb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list()

smb_direct_flush_send_list() already calls smb_direct_free_sendmsg(), so we should not call it again after post_sendmsg() moved it to the batch list.

Weakness: CWE-415

Which versions are affected by CVE-2026-31608?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-31608?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2026-31608 being exploited?

There is no known exploitation of CVE-2026-31608 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-2026-31608, DEBIAN-CVE-2026-31608, GHSA-qx6q-mqg9-4px7, UBUNTU-CVE-2026-31608.