Linux Kernel up to 6.12.111/6.18.54/7.2.8/7.3-rc4 act_ct net/sched/act_ct.c nf_ct_helper use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$5k-$25k2.27-

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.12.111/6.18.54/7.2.8/7.3-rc4 and classified as very critical. This impacts the function nf_ct_helper of the file net/sched/act_ct.c of the component act_ct. The manipulation results in use after free. This vulnerability is reported as CVE-2026-98442. The attack can be launched remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.12.111/6.18.54/7.2.8/7.3-rc4. It has been classified as very critical. Affected is the function nf_ct_helper of the file net/sched/act_ct.c of the component act_ct. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: fix helper UAF due to extensions realloc While calling the helpers, a raw pointer to the extensions area is wired into expectations list: -> nf_ct_helper() -> helper->help() -> nf_ct_expect_related_report() -> nf_ct_expect_insert() -> hlist_add_head_rcu(&exp->lnode, &master_help->expectations) In case the connection is not confirmed yet, more extensions can be added afterwards with *_ext_add() calls reallocating the extension space and leaving the now invalid pointer in the expectations list that is later accessed while removing the expectation. Make sure that helpers are called at the end after all the other extensions are already added. Note that the helper rejection now leaves the mark and labels set, but that's not different from how the NAT was handled before or how the mark and the labels were handled on confirmation failure. And there are no atomicity guarantees provided by the API anyway.

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-98442 since 09/25/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 10/18/2026).

Upgrading to version 6.12.112, 6.18.55, 7.2.9 or 7.3-rc5 eliminates this vulnerability. Applying the patch 1679bbf5fbeac52a310b1a58b2b301bbf388bdbf/812c16a255e7773a544e88b39ae6daed25544d30/8988f4d11f3fba0ab38122178836c683ad516a05/dad19b59da050cb60d3f7023dac2a042a84bf0bd is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.112/6.18.55/7.2.9/7.3-rc5
Patch: 1679bbf5fbeac52a310b1a58b2b301bbf388bdbf/812c16a255e7773a544e88b39ae6daed25544d30/8988f4d11f3fba0ab38122178836c683ad516a05/dad19b59da050cb60d3f7023dac2a042a84bf0bd

Timelineinfo

09/25/2026 CVE reserved
10/18/2026 +23 days Advisory disclosed
10/18/2026 +0 days VulDB entry created
10/18/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98442 (🔒)
GCVE (CVE): GCVE-0-2026-98442
GCVE (VulDB): GCVE-100-421782

Entryinfo

Created: 10/18/2026 17:40
Changes: 10/18/2026 17:40 (60)
Complete: 🔍
Cache ID: 216::103

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