UBUNTU-CVE-2026-23274
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.
02 / AFFECTED SOFTWARE
Affected packages
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03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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.
05 / REFERENCES
Further evidence
- https://git.kernel.org/stable/c/329f0b9b48ee6ab59d1ab72fef55fe8c6463a6cf
- https://git.kernel.org/stable/c/f228b9ae2a7e84d1153616d8e71c4236cb1f1309
- https://git.kernel.org/stable/c/f5ef97c13165542480a6ffdbe6f09f40bbb7cbf1
- https://ubuntu.com/security/CVE-2026-23274
- https://ubuntu.com/security/notices/USN-8277-1
- https://ubuntu.com/security/notices/USN-8277-2
- https://ubuntu.com/security/notices/USN-8278-1
- https://ubuntu.com/security/notices/USN-8278-2
- https://ubuntu.com/security/notices/USN-8279-1
- https://ubuntu.com/security/notices/USN-8279-2
- https://ubuntu.com/security/notices/USN-8279-3
- https://ubuntu.com/security/notices/USN-8289-1
- https://ubuntu.com/security/notices/USN-8289-2
- https://ubuntu.com/security/notices/USN-8291-1
- https://ubuntu.com/security/notices/USN-8291-2
- https://ubuntu.com/security/notices/USN-8291-3
- https://ubuntu.com/security/notices/USN-8296-1
- https://ubuntu.com/security/notices/USN-8296-2
- https://ubuntu.com/security/notices/USN-8310-1
- https://ubuntu.com/security/notices/USN-8374-1
- https://ubuntu.com/security/notices/USN-8393-1
- https://ubuntu.com/security/notices/USN-8426-1
- https://ubuntu.com/security/notices/USN-8426-2
- https://ubuntu.com/security/notices/USN-8439-1
- https://ubuntu.com/security/notices/USN-8440-1
- https://ubuntu.com/security/notices/USN-8499-1
- https://ubuntu.com/security/notices/USN-8508-1
- https://ubuntu.com/security/notices/USN-8528-1
- https://www.cve.org/CVERecord?id=CVE-2026-23274