Improper update of reference count in Linux kernel - CVE-2026-98851

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Main Vulnerability Database Vulnerabilities #VU157220

Improper update of reference count in Linux kernel - CVE-2026-98851

Published: October 22, 2026


Vulnerability identifier: #VU157220
CSH Severity: Low
CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-98851
CWE-ID: CWE-911
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local privileged user to cause a denial of service by preventing the removal of netfilter flowtables.

The vulnerability exists due to improper reference count management in nft_flow_offload_init() when nf_ct_netns_get() fails during flow offload rule initialization. A local privileged user can attempt rule additions that encounter this failure to leak flowtable references and prevent the affected flowtables from being removed.


Affected software

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-lowlatency (Ubuntu package)
linux-raspi (Ubuntu package)
linux-azure (Ubuntu package)
linux-gcp (Ubuntu package)
linux-aws (Ubuntu package)
linux-ibm (Ubuntu package)
linux-oracle (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-realtime (Ubuntu package)
linux-lowlatency-hwe-6.8 (Ubuntu package)
linux-azure-fde-6.8 (Ubuntu package)
linux-azure-6.8 (Ubuntu package)
linux-oracle-6.8 (Ubuntu package)
linux-aws-6.8 (Ubuntu package)
linux-gkeop (Ubuntu package)
linux-gke (Ubuntu package)
linux-vmware (Ubuntu package)
linux-ibm-6.8 (Ubuntu package)
linux-gcp-6.8 (Ubuntu package)
linux-aws-fips (Ubuntu package)
linux-gcp-fips (Ubuntu package)
linux-azure-fips (Ubuntu package)
linux-raspi-realtime (Ubuntu package)
linux-realtime-6.8 (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-azure-fde-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux-aws-7.0 (Ubuntu package)

How to mitigate CVE-2026-98851

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 6.8.0-149.149, 7.0.0-43.43
linux-lowlatency (Ubuntu package) - update to 6.8.0-149.149.1
linux-raspi (Ubuntu package) - addressed in versions 6.8.0-1068.72, 7.0.0-1023.23
linux-azure (Ubuntu package) - addressed in versions 6.8.0-1073.82, 7.0.0-1020.21
linux-gcp (Ubuntu package) - addressed in versions 6.8.0-1073.81, 7.0.0-1017.19
linux-aws (Ubuntu package) - addressed in versions 6.8.0-1069.74, 7.0.0-1017.18
linux-ibm (Ubuntu package) - addressed in versions 6.8.0-1069.70, 7.0.0-1018.18
linux-oracle (Ubuntu package) - addressed in versions 6.8.0-1067.71, 7.0.0-1016.18
linux-nvidia (Ubuntu package) - update to 6.8.0-1067.70
linux-realtime (Ubuntu package) - addressed in versions 6.8.1-1064.65, 7.0.0-43.43.1
linux-lowlatency-hwe-6.8 (Ubuntu package) - update to 6.8.0-149.149.1~22.04.1
linux-azure-fde-6.8 (Ubuntu package) - update to 6.8.0-1071.78~22.04.1
linux-azure-6.8 (Ubuntu package) - update to 6.8.0-1073.82~22.04.1
linux-oracle-6.8 (Ubuntu package) - update to 6.8.0-1067.71~22.04.1
linux-aws-6.8 (Ubuntu package) - update to 6.8.0-1069.74~22.04.1
linux-gkeop (Ubuntu package) - update to 6.8.0-1053.57
linux-gke (Ubuntu package) - addressed in versions 6.8.0-1068.77, 7.0.0-1010.11
linux-vmware (Ubuntu package) - update to 6.8.0-1010.10
linux-ibm-6.8 (Ubuntu package) - update to 6.8.0-1069.70~22.04.1
linux-gcp-6.8 (Ubuntu package) - update to 6.8.0-1073.81~22.04.1
linux-aws-fips (Ubuntu package) - update to 6.8.0-1069.74+fips1
linux-gcp-fips (Ubuntu package) - update to 6.8.0-1073.81+fips1
linux-azure-fips (Ubuntu package) - update to 6.8.0-1073.82+fips1
linux-raspi-realtime (Ubuntu package) - update to 6.8.0-2056.58
linux-realtime-6.8 (Ubuntu package) - update to 6.8.1-1064.65~22.04.1
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1016.18~24.04.1
linux-azure-fde-7.0 (Ubuntu package) - update to 7.0.0-1019.19~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1017.19~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1018.18
linux-azure-fde (Ubuntu package) - update to 7.0.0-1019.19
linux-aws-7.0 (Ubuntu package) - update to 7.0.0-1017.18~24.04.1

External References

Related Security Bulletins