NVD / CVE Program· CNA Linux

CVE-2023-53619: netfilter: conntrack: Avoid nf_ct_helper_hash uses after free

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: 0.22% (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 00716f25f9697d02a0d9bd622575c7c7321ba3d0, 05561f822f27b9fa88fa5504ddec34bf38833034, 4ee69c91cb8f9ca144bc0861969e5a1a3c6152a7.

Low priority for now. Upgrade to Linux Linux 00716f25f9697d02a0d9bd622575c7c7321ba3d0, 05561f822f27b9fa88fa5504ddec34bf38833034, 4ee69c91cb8f9ca144bc0861969e5a1a3c6152a7 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: conntrack: Avoid nf_ct_helper_hash uses after free If nf_conntrack_init_start() fails (for example due to a register_nf_conntrack_bpf() failure), the nf_conntrack_helper_fini() clean-up path frees the nf_ct_helper_hash map. When built with NF_CONNTRACK=y, further netfilter modules (e.g: netfilter_conntrack_ftp) can still be loaded and call nf_conntrack_helpers_register(), independently of whether nf_conntrack initialized correctly. This accesses the nf_ct_helper_hash dangling pointer and causes a uaf, possibly leading to random memory corruption. This patch guards nf_conntrack_helper_register() from accessing a freed or uninitialized nf_ct_helper_hash pointer and fixes possible uses-after-free when loading a conntrack module.

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

BDU:2026-12409

Published: Oct 7, 2025
Updated: Oct 15, 2026
EPSS: 0.2% · 12th 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 · 0.2%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 7.8
CNA · Linux: 7.8; agree

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 kernel3.6 and later · before 4.14.322
linux linux kernel4.15 and later · before 4.19.291
linux linux kernel4.20 and later · before 5.4.251
linux linux kernel5.5 and later · before 5.10.188
linux linux kernel5.11 and later · before 5.15.121
linux linux kernel5.16 and later · before 6.1.39
linux linux kernel6.2 and later · before 6.4.4
linux linux kernel6.5

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
- 3.6affected
- 12f7a505331e6b2754684b509f2ac8f0011ce644 and later · before 4ee69c91cb8f9ca144bc0861969e5a1a3c6152a7affected · git
- 12f7a505331e6b2754684b509f2ac8f0011ce644 and later · before 00716f25f9697d02a0d9bd622575c7c7321ba3d0affected · git
- 12f7a505331e6b2754684b509f2ac8f0011ce644 and later · before 61c7a5256543ae7d24cd9d21853d514c8632e1e9affected · git
- 12f7a505331e6b2754684b509f2ac8f0011ce644 and later · before 8289d422f5e484efe4a565fe18e862ecd621c175affected · git
- 12f7a505331e6b2754684b509f2ac8f0011ce644 and later · before 6f03ce2f1abcb9f9d0511e3659ca6eb60e39f566affected · git
- 12f7a505331e6b2754684b509f2ac8f0011ce644 and later · before 05561f822f27b9fa88fa5504ddec34bf38833034affected · git
- 12f7a505331e6b2754684b509f2ac8f0011ce644 and later · before fce5cc7cbd4b92f979bf02c9ec5fb69aaeba92d7affected · git
- 12f7a505331e6b2754684b509f2ac8f0011ce644 and later · before 6eef7a2b933885a17679eb8ed0796ddf0ee5309baffected · git
- before 3.6not 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 6.1.52-1	6.1.52-1
Debian:13	linux	before 6.4.4-1	6.4.4-1

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-2022-50552Oct 7, 2025 · blk-mq: use quiesced elevator switch when reinitializing queues
31Monitor
← EarlierCVE-2022-50553Oct 7, 2025 · tracing/hist: Fix out-of-bound write on 'action_data.var_ref_idx'
22Monitor
Later →CVE-2023-53620Oct 7, 2025 · md: fix soft lockup in status_resync
22Monitor

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	00716f25f9697d02a0d9bd622575c7c7321ba3d0	Vendor (CNA)
Linux Linux	05561f822f27b9fa88fa5504ddec34bf38833034	Vendor (CNA)
Linux Linux	4ee69c91cb8f9ca144bc0861969e5a1a3c6152a7	Vendor (CNA)
Linux Linux	61c7a5256543ae7d24cd9d21853d514c8632e1e9	Vendor (CNA)
Linux Linux	6eef7a2b933885a17679eb8ed0796ddf0ee5309b	Vendor (CNA)
Linux Linux	6f03ce2f1abcb9f9d0511e3659ca6eb60e39f566	Vendor (CNA)
Linux Linux	8289d422f5e484efe4a565fe18e862ecd621c175	Vendor (CNA)
Linux Linux	fce5cc7cbd4b92f979bf02c9ec5fb69aaeba92d7	Vendor (CNA)
debian:linux	6.1.52-1 · 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-primary

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 15, 2026, 11:07 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/00716f25f9697d02a0d9bd622575c7c7321ba3d0

Show all references (7 more)

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

All records