CVE-2026-74492

/// Technical description

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 add

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References