Status: UPDATED | Advisory ID: CVE-2026-23458
| CVE | CVE-2026-23458 |
| CVSS Score / Version | 7.8 (High) / CVSS v3.1 |
| Updated | 2026-07-24 |
| CVSS Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| CVSS Prose | attack vector is local; attack complexity is low; privileges required is low; user interaction is none; scope is unchanged; confidentiality impact is high; integrity impact is high; availability impact is high. |
| Affected products | Linux Linux Kernel |
| Classified as | CWE-416 (Use After Free) |
| Vendor | Product | Affected Versions | Patch Status |
|---|---|---|---|
| Linux | Linux Kernel |
| Subsystems | General OT |
| Sectors | All Sectors |
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->data 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->ext.
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->args[0] early-return check in the dump
callback to avoid dereferencing ct->ext 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:
<TASK>
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 (NVD)
Monitor Linux's web page for any future patch releases.
| Source | Reference |
|---|---|
| NVD | https://nvd.nist.gov/vuln/detail/CVE-2026-23458 |
| CVE | https://www.cve.org/CVERecord?id=CVE-2026-23458 |