Linux Kernel up to 6.18.23/6.19.13/7.0.0 smb_direct_flush_send_list double free

Summaryinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.18.23/6.19.13/7.0.0. Affected by this issue is the function smb_direct_flush_send_list. This manipulation causes double free. This vulnerability is tracked as CVE-2026-31608. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.18.23/6.19.13/7.0.0 and classified as critical. Affected by this vulnerability is the function smb_direct_flush_send_list. The manipulation with an unknown input leads to a double free vulnerability. The CWE definition for the vulnerability is CWE-415. The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations. The impact remains unknown. The summary by CVE is:

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.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-31608 since 03/09/2026. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 04/24/2026).

Upgrading to version 6.18.24, 6.19.14 or 7.0.1 eliminates this vulnerability. Applying the patch 6968c91fab05b8fc4d6700e0cf34472bb422df25/2ba03f46132b0d1a7bafb86e1ef61951a2254023/830de6eeb9db4cb7e758201fb99328ef4ca4b032 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3
• 6.19.4
• 6.19.5
• 6.19.6
• 6.19.7
• 6.19.8
• 6.19.9
• 6.19.10
• 6.19.11
• 6.19.12
• 6.19.13
• 7.0

License

• open-source

Website

• Vendor: https://www.kernel.org/

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