Linux Kernel up to 6.18.52/7.2.6/7.3-rc2 cttimeout ctnl_timeout_find_get use after free

CVSS Meta Temp Score
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CTI Interest Score
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7.8$0-$5k0.00

Summaryinfo

A vulnerability classified as very critical has been found in Linux Kernel up to 6.18.52/7.2.6/7.3-rc2. The impacted element is the function ctnl_timeout_find_get of the component cttimeout. The manipulation leads to use after free. This vulnerability is uniquely identified as CVE-2026-97609. Local access is required to approach this attack. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in Linux Kernel up to 6.18.52/7.2.6/7.3-rc2. This issue affects the function ctnl_timeout_find_get of the component cttimeout. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: netfilter: cttimeout: prevent UAF during module unload nf_ct_set_timeout() protects the timeout hook dereference and policy lookup with rcu_read_lock(). cttimeout_exit(), however, unregisters the per-net operations before it clears the hook. This allows the following interleaving: CPU 0 CPU 1 cttimeout_exit() nf_ct_set_timeout() unregister_pernet_subsys() rcu_read_lock() kfree(pernet) h = nf_ct_timeout_hook h->timeout_find_get() nfct_timeout_pernet() The hook still points to ctnl_timeout_find_get() when CPU 1 looks up the already freed per-net timeout list. KASAN reported: BUG: KASAN: slab-use-after-free in ctnl_timeout_find_get Read of size 8 by task poc/90 Call Trace: ctnl_timeout_find_get+0x271/0x2a0 [nfnetlink_cttimeout] nf_ct_set_timeout+0x7b/0x3c0 xt_ct_tg_check+0x724/0xb20 xt_check_target+0x234/0xa90 do_ipt_set_ctl+0x570/0x1270 Allocated by task 89: __kmalloc_noprof+0x16e/0x460 ops_init+0x6d/0x420 register_pernet_operations+0x2f6/0x670 Freed by task 91: kfree+0x131/0x390 ops_undo_list+0x3d4/0x730 unregister_pernet_operations+0x232/0x490 unregister_pernet_subsys+0x1c/0x30 cttimeout_exit+0x52/0x970 [nfnetlink_cttimeout] Clear the hook and wait for existing readers before unregistering the per-net operations. This blocks new policy lookups and ensures readers that observed the hook finish before the per-net storage is freed.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2026-97609 since 09/24/2026. The exploitation is known to be easy. Attacking locally is a requirement. Additional levels of successful authentication are required for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/25/2026).

Upgrading to version 6.18.53, 7.2.7 or 7.3-rc3 eliminates this vulnerability. Applying the patch a7fdd86c386b7f7cc72a126389c2cdb55d035221/1f69c570a73f2dedf75ea5166d47622d5fa958c1/fec9b1de0d02de8dafa3cc344bcb91cf28660643 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: 8.2
VulDB Meta Temp Score: 7.8

VulDB Base Score: 8.2
VulDB Temp Score: 7.8
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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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: Partially
Local: Yes
Remote: No

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 6.18.53/7.2.7/7.3-rc3
Patch: a7fdd86c386b7f7cc72a126389c2cdb55d035221/1f69c570a73f2dedf75ea5166d47622d5fa958c1/fec9b1de0d02de8dafa3cc344bcb91cf28660643

Timelineinfo

09/24/2026 CVE reserved
09/25/2026 +1 days Advisory disclosed
09/25/2026 +0 days VulDB entry created
09/25/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-97609 (🔒)
GCVE (CVE): GCVE-0-2026-97609
GCVE (VulDB): GCVE-100-410087

Entryinfo

Created: 09/25/2026 14:30
Changes: 09/25/2026 14:30 (59)
Complete: 🔍
Cache ID: 216::103

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