CVE-2026-74492
HighCVSS 8.4Exploitation Probability (EPSS)
Low risk4th percentile - higher than 4% of all known CVEs
Summary
In netfilter ipset, there is an issue with updating comments from kernel-side operations. During table resize, comment pointers are copied, and a packet-side update can free a shared comment, leading to use of a dangling pointer.
Risk Assessment
An attacker could exploit this to cause a system crash or potentially execute code in the kernel, posing a serious security threat.
Recommendation
Update the Linux kernel to a version with the fix that skips comment updates for packet-side operations.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: do not update comments from kernel-side hash adds mtype_resize() copies comment pointers with memcpy(), not the comment objects themselves. During the window after an entry has been copied but before the table swap and backlog replay, the old table is still published for packet-side updates while the replacement-table entry already holds the same ip_set_comment_rcu pointer. If xt_SET --add-set ... --exist hits that old entry in this window, mtype_add() calls ip_set_init_comment() even though packet-side adds carry no comment payload. That call frees the shared comment through the old entry, so the replacement-table entry now holds a stale pointer. When the queued add is replayed on the new table, mtype_add() calls ip_set_init_comment() again and strlen() dereferences the stale pointer. Fix this in mtype_add() by skipping ip_set_init_comment() when ext->target marks a packet-side add. Userspace adds still update comments, while packet-side adds can no longer free comment storage shared with a resize copy.