Linux Kernel up to 6.19.12 netfilter nfnetlink_cttimeout.c nft_ct_timeout_obj_destroy use after free

CVSS Meta Temp Score
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CTI Interest Score
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7.7$0-$5k0.00

Summaryinfo

A vulnerability has been found in Linux Kernel up to 6.19.12 and classified as critical. Affected by this issue is the function nft_ct_timeout_obj_destroy of the file nfnetlink_cttimeout.c of the component netfilter. Performing a manipulation results in use after free. This vulnerability is identified as CVE-2026-31665. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.19.12. This affects the function nft_ct_timeout_obj_destroy of the file nfnetlink_cttimeout.c of the component netfilter. 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. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_ct: fix use-after-free in timeout object destroy nft_ct_timeout_obj_destroy() frees the timeout object with kfree() immediately after nf_ct_untimeout(), without waiting for an RCU grace period. Concurrent packet processing on other CPUs may still hold RCU-protected references to the timeout object obtained via rcu_dereference() in nf_ct_timeout_data(). Add an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer freeing until after an RCU grace period, matching the approach already used in nfnetlink_cttimeout.c. KASAN report: BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0 Read of size 4 at addr ffff8881035fe19c by task exploit/80 Call Trace: nf_conntrack_tcp_packet+0x1381/0x29d0 nf_conntrack_in+0x612/0x8b0 nf_hook_slow+0x70/0x100 __ip_local_out+0x1b2/0x210 tcp_sendmsg_locked+0x722/0x1580 __sys_sendto+0x2d8/0x320 Allocated by task 75: nft_ct_timeout_obj_init+0xf6/0x290 nft_obj_init+0x107/0x1b0 nf_tables_newobj+0x680/0x9c0 nfnetlink_rcv_batch+0xc29/0xe00 Freed by task 26: nft_obj_destroy+0x3f/0xa0 nf_tables_trans_destroy_work+0x51c/0x5c0 process_one_work+0x2c4/0x5a0

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-31665 since 03/09/2026. The exploitability is told to be easy. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/17/2026).

The vulnerability scanner Nessus provides a plugin with the ID 326222 (EulerOS 2.0 SP12 : kernel (EulerOS-SA-2026-2535)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.253, 5.15.203, 6.1.169, 6.6.135, 6.12.82, 6.18.23 or 6.19.13 eliminates this vulnerability. Applying the patch c458fc1c278a65ad5381083121d39a479973ebed/c581e5c8f2b59158f62efe61c1a3dc36189081ff/f16fe84879a5280f05ebbcea593a189ba0f3e79a/070abdf1b04325b21a20a2a0c39a2208af107275/aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77/b42aca3660dc2627a29a38131597ca610dc451f9/d0983b48c10d1509fd795c155f8b1e832e1369ff/f8dca15a1b190787bbd03285304b569631160eda is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (326222) and EUVD (EUVD-2026-25558). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.9
VulDB Meta Temp Score: 7.7

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.8
CNA Vector (Linux): 🔒

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: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 326222
Nessus Name: EulerOS 2.0 SP12 : kernel (EulerOS-SA-2026-2535)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.253/5.15.203/6.1.169/6.6.135/6.12.82/6.18.23/6.19.13
Patch: c458fc1c278a65ad5381083121d39a479973ebed/c581e5c8f2b59158f62efe61c1a3dc36189081ff/f16fe84879a5280f05ebbcea593a189ba0f3e79a/070abdf1b04325b21a20a2a0c39a2208af107275/aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77/b42aca3660dc2627a29a38131597ca610dc451f9/d0983b48c10d1509fd795c155f8b1e832e1369ff/f8dca15a1b190787bbd03285304b569631160eda

Timelineinfo

03/09/2026 CVE reserved
04/24/2026 +45 days Advisory disclosed
04/24/2026 +0 days VulDB entry created
07/17/2026 +84 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-31665 (🔒)
GCVE (CVE): GCVE-0-2026-31665
GCVE (VulDB): GCVE-100-359481
EUVD: 🔒

Entryinfo

Created: 04/24/2026 19:04
Updated: 07/17/2026 10:03
Changes: 04/24/2026 19:04 (60), 04/24/2026 19:35 (1), 07/10/2026 13:05 (2), 07/17/2026 10:03 (11)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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