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Vulnerabilities

Vulnerability · CVE-2026-98851

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_flow_offload: drop flowtable reference on init error path nft_flow_offload_init() bumps the flowt

Published Oct 19, 2026 · catalog updated Oct 20, 2026 · In the Linux kernel,

Open the advisory

Exploitation likelihood is not on this record for CVE-2026-98851. A missing EPSS score is not a low risk. Compare In the Linux kernel, with the linked advisory before you change production.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (In the Linux kernel,).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
  • EPSS is missing. A missing score is not a low risk.
Severity
Unknown—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
Awaiting synchronization with FIRST
Remediation
Advisory link
Affected products
Ubuntu:16.04:LTS linux-hwe-edge · Ubuntu:18.04:LTS linux-aws-5.0 · Ubuntu:18.04:LTS linux-aws-5.3 · Ubuntu:18.04:LTS linux-azure · Ubuntu:18.04:LTS linux-azure-5.3 · Ubuntu:18.04:LTS linux-azure-edge

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_flow_offload: drop flowtable reference on init error path nft_flow_offload_init() bumps the flowtable use count with nft_use_inc() before calling nf_ct_netns_get(). When the latter fails, the error is returned as-is and the reference is leaked. The upper layers do not balance it either: nf_tables_newexpr() clears expr->ops when the expression init callback fails, so the nft_expr_more() iteration in nft_rule_expr_deactivate() and nf_tables_rule_destroy() stops right before the failed expression and its ->destroy callback, which would drop the reference, never runs. Each failed rule addition therefore leaks one flowtable reference and the flowtable can no longer be removed: NFT_MSG_DELFLOWTABLE keeps reporting -EBUSY even though no rule references it. Save the nf_ct_netns_get() return value and undo the nft_use_inc() when it fails, restoring the inc/dec pairing within nft_flow_offload_init() itself.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Ubuntu:16.04:LTS linux-hwe-edge4.8.0-28.30~16.04.1, 4.8.0-30.32~16.04.1, 4.8.0-32.34~16.04.1
  • Ubuntu:18.04:LTS linux-aws-5.05.0.0-1021.24~18.04.1, 5.0.0-1022.25~18.04.1, 5.0.0-1023.26~18.04.1
  • Ubuntu:18.04:LTS linux-aws-5.35.3.0-1016.17~18.04.1, 5.3.0-1017.18~18.04.1, 5.3.0-1019.21~18.04.1
  • Ubuntu:18.04:LTS linux-azure4.15.0-1002.2, 4.15.0-1003.3, 4.15.0-1004.4
  • Ubuntu:18.04:LTS linux-azure-5.35.3.0-1007.8~18.04.1, 5.3.0-1008.9~18.04.1, 5.3.0-1009.10~18.04.1
  • Ubuntu:18.04:LTS linux-azure-edge4.18.0-1006.6~18.04.1, 4.18.0-1007.7~18.04.1, 4.18.0-1008.8~18.04.1
  • Ubuntu:18.04:LTS linux-gcp4.15.0-1001.1, 4.15.0-1003.3, 4.15.0-1005.5
  • Ubuntu:18.04:LTS linux-gcp-5.35.3.0-1008.9~18.04.1, 5.3.0-1009.10~18.04.1, 5.3.0-1010.11~18.04.1
  • Ubuntu:18.04:LTS linux-gke-4.154.15.0-1030.32, 4.15.0-1032.34, 4.15.0-1033.35
  • Ubuntu:Pro:18.04:LTS linux-aws-5.45.4.0-1018.18~18.04.1, 5.4.0-1020.20~18.04.2, 5.4.0-1022.22~18.04.1
  • Ubuntu:Pro:18.04:LTS linux-azure-5.45.4.0-1020.20~18.04.1, 5.4.0-1022.22~18.04.1, 5.4.0-1023.23~18.04.1
  • Ubuntu:Pro:18.04:LTS linux-gcp-5.45.4.0-1019.19~18.04.2, 5.4.0-1021.21~18.04.1, 5.4.0-1022.22~18.04.1

How to fix CVE-2026-98851

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

Exploitation likelihood is not on this record for CVE-2026-98851. A missing EPSS score is not a low risk. Compare In the Linux kernel, with the linked advisory before you change production.

Which versions are affected?

Compare what you have installed with 4.8.0-28.30~16.04.1, 4.8.0-30.32~16.04.1, 4.8.0-32.34~16.04.1, 5.0.0-1021.24~18.04.1, 5.0.0-1022.25~18.04.1, 5.0.0-1023.26~18.04.1, 5.3.0-1016.17~18.04.1, 5.3.0-1017.18~18.04.1, 5.3.0-1019.21~18.04.1, 4.15.0-1002.2, 4.15.0-1003.3, 4.15.0-1004.4, 5.3.0-1007.8~18.04.1, 5.3.0-1008.9~18.04.1, 5.3.0-1009.10~18.04.1, 4.18.0-1006.6~18.04.1, 4.18.0-1007.7~18.04.1, 4.18.0-1008.8~18.04.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS is not on this record yet. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Ubuntu security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 19, 2026 · OpenSSF OSV / OSV Scanner

    Detected

    In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_flow_offload: drop flowtable reference on init error path nft_flow_offload_init() bumps the flowtable use count with nft_use_inc() before calling nf_ct_netns_get(). When the latter fails, the error is returned as-is and the reference is leaked. The upper layers do not balance it either: nf_tables_newexpr() clears ex

  2. Oct 20, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_flow_offload: drop flowtable reference on init error path nft_flow_offload_init() bumps the flowtable use count with nft_use_inc() before calling nf_ct_netns_get(). When the latter fails, the error is returned as-is and the reference is leaked. The upper layers do not balance it either: nf_tables_newexpr() clears ex

Sources

References

Freshness

Last verified in this catalog Oct 20, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.