Linux Kernel up to 6.18.20/6.19.10 DAMON Sysfs Interface damon_sysfs_repeat_call_fn null pointer dereference

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 6.18.20/6.19.10. Impacted is the function damon_sysfs_repeat_call_fn of the component DAMON Sysfs Interface. The manipulation leads to null pointer dereference. This vulnerability is listed as CVE-2026-31457. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.18.20/6.19.10. This issue affects the function damon_sysfs_repeat_call_fn of the component DAMON Sysfs Interface. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs: check contexts->nr in repeat_call_fn damon_sysfs_repeat_call_fn() calls damon_sysfs_upd_tuned_intervals(), damon_sysfs_upd_schemes_stats(), and damon_sysfs_upd_schemes_effective_quotas() without checking contexts->nr. If nr_contexts is set to 0 via sysfs while DAMON is running, these functions dereference contexts_arr[0] and cause a NULL pointer dereference. Add the missing check. For example, the issue can be reproduced using DAMON sysfs interface and DAMON user-space tool (damo) [1] like below. $ sudo damo start --refresh_interval 1s $ echo 0 | sudo tee \ /sys/kernel/mm/damon/admin/kdamonds/0/contexts/nr_contexts

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-31457 since 03/09/2026. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 310608 (Linux Distros Unpatched Vulnerability : CVE-2026-31457), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.18.21 or 6.19.11 eliminates this vulnerability. Applying the patch 3527e9fdc38570cea0f6ddb7a2c9303d4044b217/652cd0641a763dd0e846b0d12814977fadb2b7d8/6557004a8b59c7701e695f02be03c7e20ed1cc15 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.

The vulnerability is also documented in the databases at Tenable (310608) and CERT Bund (WID-SEC-2026-1252). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

• Google Container-Optimized OS
• Debian Linux
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Open Source Linux Kernel

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
• 6.19.0
• 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

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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Exploitinginfo

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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