CVE-2026-31457 mm/damon/sysfs: check contexts->nr in repeat_call_fn

What is CVE-2026-31457?

CVE-2026-31457 is a medium-severity vulnerability in Linux kernel, published on 22 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:

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

Weakness: CWE-476

Which versions are affected by CVE-2026-31457?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-31457?

Apply the vendor's patch.

Is CVE-2026-31457 being exploited?

There is no known exploitation of CVE-2026-31457 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-2026-31457, DEBIAN-CVE-2026-31457, GHSA-p6jg-gm5j-8f2r, UBUNTU-CVE-2026-31457.