NVD / CVE Program· CNA Linux

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

Noroxi assessment

Priority: Monitor (action score 31/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.13% (FIRST EPSS).
Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
Fixed version: Linux Linux 04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56, 5cb81eeda909dbb2def209dd10636b51549a3f8a, 9821b47f669eb82791fa0b1a6ebaf9aa219bea72.

Low priority for now. Upgrade to Linux Linux 04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56, 5cb81eeda909dbb2def209dd10636b51549a3f8a, 9821b47f669eb82791fa0b1a6ebaf9aa219bea72 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

BDU:2026-10895

Published: Apr 3, 2026
Updated: Oct 19, 2026
EPSS: 0.1% · 2th percentile
CWE: CWE-416

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 31 / 40 · 7.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.1%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · Linux: 7.8; NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
linux	linux kernel	cpe:2.3:o:linux:linux_kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

linux linux kernel3.10 and later · before 5.10.253
linux linux kernel5.11 and later · before 5.15.203
linux linux kernel5.16 and later · before 6.1.167
linux linux kernel6.2 and later · before 6.6.130
linux linux kernel6.7 and later · before 6.12.78
linux linux kernel6.13 and later · before 6.18.20
linux linux kernel6.19 and later · before 6.19.10
linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

Linux Linux
- 3.10affected
- e844a928431fa8f1359d1f4f2cef53d9b446bf52 and later · before d8cd0efbccc5cfb0a80da744a7da76e1333ab925affected · git
- e844a928431fa8f1359d1f4f2cef53d9b446bf52 and later · before 9821b47f669eb82791fa0b1a6ebaf9aa219bea72affected · git
- e844a928431fa8f1359d1f4f2cef53d9b446bf52 and later · before bdf2724eefd4455a66863abb025bab8d3aa98c57affected · git
- e844a928431fa8f1359d1f4f2cef53d9b446bf52 and later · before f04cc86d59906513d2d62183b882966fc0ae0390affected · git
- e844a928431fa8f1359d1f4f2cef53d9b446bf52 and later · before f025171feef2ac65663d7986f1d5ff0c28d6b2a9affected · git
- e844a928431fa8f1359d1f4f2cef53d9b446bf52 and later · before 04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56affected · git
- e844a928431fa8f1359d1f4f2cef53d9b446bf52 and later · before cd541f15b60e2257441398cf495d978f816d09f8affected · git
- e844a928431fa8f1359d1f4f2cef53d9b446bf52 and later · before 5cb81eeda909dbb2def209dd10636b51549a3f8aaffected · git
- before 3.10not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	linux	before 6.1.170-1	6.1.170-1
Debian:13	linux	before 6.12.85-1	6.12.85-1
Debian:14	linux	before 6.19.10-1	6.19.10-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
90Now
CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
89Now
CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
85Now

Published before and after this one in the same product

← EarlierCVE-2026-23456Apr 3, 2026 · netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case
32Monitor
← EarlierCVE-2026-23457Apr 3, 2026 · netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()
34Monitor
Later →CVE-2026-23459Apr 3, 2026 · ip_tunnel: adapt iptunnel_xmit_stats() to NETDEV_PCPU_STAT_DSTATS
32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
Linux Linux	04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56	Vendor (CNA)
Linux Linux	5cb81eeda909dbb2def209dd10636b51549a3f8a	Vendor (CNA)
Linux Linux	9821b47f669eb82791fa0b1a6ebaf9aa219bea72	Vendor (CNA)
Linux Linux	bdf2724eefd4455a66863abb025bab8d3aa98c57	Vendor (CNA)
Linux Linux	cd541f15b60e2257441398cf495d978f816d09f8	Vendor (CNA)
Linux Linux	d8cd0efbccc5cfb0a80da744a7da76e1333ab925	Vendor (CNA)
Linux Linux	f025171feef2ac65663d7986f1d5ff0c28d6b2a9	Vendor (CNA)
Linux Linux	f04cc86d59906513d2d62183b882966fc0ae0390	Vendor (CNA)
debian:linux	6.1.170-1 · Debian:12	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Someone with local access to the system can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Local
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

SSVC exploitation— → noneOct 16, 2026, 5:07 PM UTC
Fix✗ → ✓Sep 28, 2026, 10:10 PM UTC

For records you follow, these changes also arrive as notifications. →

References

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

Show all references (10 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records