CVE-2026-23274

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_IDLETIMER: reject rev0 reuse of ALARM timer labels IDLETIMER revision 0 rules reuse existing timers by label and always call mod_timer() on timer->timer. If the label was created first by revision 1 with XT_IDLETIMER_ALARM, the object uses alarm timer semantics and timer->timer is never initialized. Reusing that object from revision 0 causes mod_timer() on an uninitialized timer_list, triggering debugobjects warnings and possible panic when panic_on_warn=1. Fix this by rejecting revision 0 rule insertion when an existing timer with the same label is of ALARM type.

References

• https://git.kernel.org/stable/c/28c7cfaf0c0ab17cbd7754092116fd1af45271f9
• https://git.kernel.org/stable/c/329f0b9b48ee6ab59d1ab72fef55fe8c6463a6cf
• https://git.kernel.org/stable/c/54080355999381fed4a26129579a5765bab87491
• https://git.kernel.org/stable/c/5e7ece24c5cb75a60402aad4d803c7898ea40aa9
• https://git.kernel.org/stable/c/f228b9ae2a7e84d1153616d8e71c4236cb1f1309