{"id":"DEBIAN-CVE-2026-23458","details":"In the Linux kernel, the following vulnerability has been resolved:  netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()  ctnetlink_dump_exp_ct() stores a conntrack pointer in cb-\u003edata for the netlink dump callback ctnetlink_exp_ct_dump_table(), but drops the conntrack reference immediately after netlink_dump_start().  When the dump spans multiple rounds, the second recvmsg() triggers the dump callback which dereferences the now-freed conntrack via nfct_help(ct), leading to a use-after-free on ct-\u003eext.  The bug is that the netlink_dump_control has no .start or .done callbacks to manage the conntrack reference across dump rounds.  Other dump functions in the same file (e.g. ctnetlink_get_conntrack) properly use .start/.done callbacks for this purpose.  Fix this by adding .start and .done callbacks that hold and release the conntrack reference for the duration of the dump, and move the nfct_help() call after the cb-\u003eargs[0] early-return check in the dump callback to avoid dereferencing ct-\u003eext unnecessarily.   BUG: KASAN: slab-use-after-free in ctnetlink_exp_ct_dump_table+0x4f/0x2e0  Read of size 8 at addr ffff88810597ebf0 by task ctnetlink_poc/133   CPU: 1 UID: 0 PID: 133 Comm: ctnetlink_poc Not tainted 7.0.0-rc2+ #3 PREEMPTLAZY  Call Trace:   \u003cTASK\u003e   ctnetlink_exp_ct_dump_table+0x4f/0x2e0   netlink_dump+0x333/0x880   netlink_recvmsg+0x3e2/0x4b0   ? aa_sk_perm+0x184/0x450   sock_recvmsg+0xde/0xf0   Allocated by task 133:   kmem_cache_alloc_noprof+0x134/0x440   __nf_conntrack_alloc+0xa8/0x2b0   ctnetlink_create_conntrack+0xa1/0x900   ctnetlink_new_conntrack+0x3cf/0x7d0   nfnetlink_rcv_msg+0x48e/0x510   netlink_rcv_skb+0xc9/0x1f0   nfnetlink_rcv+0xdb/0x220   netlink_unicast+0x3ec/0x590   netlink_sendmsg+0x397/0x690   __sys_sendmsg+0xf4/0x180   Freed by task 0:   slab_free_after_rcu_debug+0xad/0x1e0   rcu_core+0x5c3/0x9c0","modified":"2026-09-01T16:06:35.565443090Z","published":"2026-04-03T16:16:32.647Z","upstream":["CVE-2026-23458"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-23458"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.170-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.129-1","6.1.133-1","6.1.135-1","6.1.137-1","6.1.139-1","6.1.140-1","6.1.147-1","6.1.148-1","6.1.153-1","6.1.158-1","6.1.159-1","6.1.162-1","6.1.164-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not 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