Exposure of resource to wrong sphere in Linux kernel - CVE-2026-23274

Detailed vulnerability description

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to improper input validation in the netfilter xt_IDLETIMER module when processing timer rules with reused labels. A local user can insert a revision 0 IDLETIMER rule with a label that was previously used by a revision 1 rule with XT_IDLETIMER_ALARM, leading to modification of an uninitialized timer_list object, which can trigger debugobjects warnings and potentially cause a kernel panic when panic_on_warn=1 is enabled.

Exploitation requires the ability to load netfilter rules. The impact is limited to denial of service via system crash under specific kernel configurations.

How to mitigate CVE-2026-23274

Sources

• https://git.kernel.org/stable/c/329f0b9b48ee6ab59d1ab72fef55fe8c6463a6cf
• https://git.kernel.org/stable/c/f228b9ae2a7e84d1153616d8e71c4236cb1f1309
• https://git.kernel.org/stable/c/f5ef97c13165542480a6ffdbe6f09f40bbb7cbf1