CVE-2026-23458

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-04-03. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
7.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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: 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

CVSS v3
7.8
EG Score
7.8(medium)
EPSS
3.1%
KEV
Not listed

Published

April 3, 2026

Last Modified

July 14, 2026

Advisory Details (10)

Auto-updated Jul 14, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic🔴 Active Exploitation

SSA-082556

https://cert-portal.siemens.com/productcert/html/ssa-082556.html
generic

SSA-019113

https://cert-portal.siemens.com/productcert/html/ssa-019113.html
generic

netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/f04cc86d59906513d2d62183b882966fc0ae0390
generic

netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/f025171feef2ac65663d7986f1d5ff0c28d6b2a9
generic

netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d8cd0efbccc5cfb0a80da744a7da76e1333ab925
generic

netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/cd541f15b60e2257441398cf495d978f816d09f8
generic

netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/bdf2724eefd4455a66863abb025bab8d3aa98c57
generic

netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/9821b47f669eb82791fa0b1a6ebaf9aa219bea72
generic

netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/5cb81eeda909dbb2def209dd10636b51549a3f8a
generic

netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56

Vendor Advisories for CVE-2026-23458(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
linuxKernel @ 5.10.253—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 14× in last 7d / 49× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 112 total refreshes for this CVE.

  1. 2026-07-18 10:04 UTCEPSS rescore
  2. 2026-07-18 10:04 UTCEPSS rescore
  3. 2026-07-17 03:24 UTCOSV refresh
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  33. 2026-06-11 22:02 UTCGHSA enrichment
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  36. 2026-06-10 13:37 UTCGHSA enrichment
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  40. 2026-06-08 14:17 UTCEPSS rescore
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  42. 2026-06-08 09:41 UTCGHSA enrichment
  43. 2026-06-07 22:18 UTCGHSA enrichment
  44. 2026-06-07 15:25 UTCEPSS rescore
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  46. 2026-06-07 10:55 UTCGHSA enrichment
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Frequently asked(5)

What is CVE-2026-23458?
CVE-2026-23458 is a high vulnerability published on April 3, 2026. In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: fix use-after-free in ctnetlinkdumpexp_ct() ctnetlinkdumpexp_ct() stores a conntrack pointer in cb->data for the netlink dump callback ctnetlinkexpctdumptable(), but drops the conntrack reference immediately…
When was CVE-2026-23458 disclosed?
CVE-2026-23458 was first published in the National Vulnerability Database on April 3, 2026, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-23458 actively exploited?
CVE-2026-23458 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-23458?
CVE-2026-23458 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-23458?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23458, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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