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CVE-2026-23458— netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于ctnetlink_dump_exp_ct函数存在释放后重用，可能导致空指针取消引用。

CVSS 7.8 · High EPSS 0.13% · P3

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux e844a928431fa8f1359d1f4f2cef53d9b446bf52< d8cd0efbccc5cfb0a80da744a7da76e1333ab925 affected
e844a928431fa8f1359d1f4f2cef53d9b446bf52< 9821b47f669eb82791fa0b1a6ebaf9aa219bea72 affected
e844a928431fa8f1359d1f4f2cef53d9b446bf52< bdf2724eefd4455a66863abb025bab8d3aa98c57 affected
e844a928431fa8f1359d1f4f2cef53d9b446bf52< f04cc86d59906513d2d62183b882966fc0ae0390 affected
e844a928431fa8f1359d1f4f2cef53d9b446bf52< f025171feef2ac65663d7986f1d5ff0c28d6b2a9 affected
e844a928431fa8f1359d1f4f2cef53d9b446bf52< 04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56 affected
e844a928431fa8f1359d1f4f2cef53d9b446bf52< cd541f15b60e2257441398cf495d978f816d09f8 affected
e844a928431fa8f1359d1f4f2cef53d9b446bf52< 5cb81eeda909dbb2def209dd10636b51549a3f8a affected
… +10 more rows
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I. Basic Information for CVE-2026-23458

Vulnerability Information
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Vulnerability Title
netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()
Source: CVE Program / CVE List V5
Vulnerability Description
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
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于ctnetlink_dump_exp_ct函数存在释放后重用，可能导致空指针取消引用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux e844a928431fa8f1359d1f4f2cef53d9b446bf52 ~ d8cd0efbccc5cfb0a80da744a7da76e1333ab925 -
Linux Linux 3.10 -

II. Public POCs for CVE-2026-23458

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-23458

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Same Patch Batch · Linux · 2026-04-03 · 71 CVEs total

CVE-2026-31402 9.8 CRITICAL nfsd: fix heap overflow in NFSv4.0 LOCK replay cache
CVE-2026-23450 9.8 CRITICAL net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock()
CVE-2026-23427 9.8 CRITICAL ksmbd: fix use-after-free in durable v2 replay of active file handles
CVE-2026-23428 9.8 CRITICAL ksmbd: fix use-after-free of share_conf in compound request
CVE-2026-23455 9.1 CRITICAL netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()
CVE-2026-23461 8.8 HIGH Bluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user
CVE-2026-23425 8.8 HIGH KVM: arm64: Fix ID register initialization for non-protected pKVM guests
CVE-2026-23462 8.8 HIGH Bluetooth: HIDP: Fix possible UAF
CVE-2026-23457 8.6 HIGH netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()
CVE-2026-23456 8.2 HIGH netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case
CVE-2026-23459 8.2 HIGH ip_tunnel: adapt iptunnel_xmit_stats() to NETDEV_PCPU_STAT_DSTATS
CVE-2026-31393 8.1 HIGH Bluetooth: L2CAP: Validate L2CAP_INFO_RSP payload length before access
CVE-2026-31392 8.1 HIGH smb: client: fix krb5 mount with username option
CVE-2026-23466 7.8 HIGH drm/xe: Open-code GGTT MMIO access protection
CVE-2026-23432 7.8 HIGH mshv: Fix use-after-free in mshv_map_user_memory error path
CVE-2026-31398 7.8 HIGH mm/rmap: fix incorrect pte restoration for lazyfree folios
CVE-2026-23437 7.8 HIGH net: shaper: protect late read accesses to the hierarchy
CVE-2026-23444 7.8 HIGH wifi: mac80211: always free skb on ieee80211_tx_prepare_skb() failure
CVE-2026-23449 7.8 HIGH net/sched: teql: Fix double-free in teql_master_xmit
CVE-2026-23445 7.8 HIGH igc: fix page fault in XDP TX timestamps handling

Showing top 20 of 71 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23458

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