Reference leak in Linux kernel nftables flow offload init
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 5 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
The Linux kernel from 4.16 is affected by a reference leak in the nft_flow_offload_init function of netfilter. The function increments the flowtable use count but does not release it when nf_ct_netns_get fails. Each failed rule addition leaks one flowtable reference, so the flowtable can no longer be deleted even though no rule uses it.
Written with Claude Haiku 5.5 from the sources below · 2026-11-07
Description from the CNA
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.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 4.16 and later | 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10, 7.3 | Patch available | CNA |
- Linux VendorLinux Affected 4.16 and later Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10, 7.3 Patch available CNA
Remediation
The Linux kernel is fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10 and 7.3. Red Hat lists Red Hat Enterprise Linux 8, 9 and 10 and Red Hat OpenShift Container Platform 4 and 5 as affected, with no fix available.
Written with Claude Haiku 5.5 from the sources below · 2026-11-07
- Fix · CNA Linux (Linux) Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10, 7.3
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 2 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98851
- 2026-10-18 Alias added: GHSA-95vh-jxqc-h2w9
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Fix available: Linux/Linux@1d27214fd9a4d2c0c6d998fc9d4fb61448a3438e, Linux/[email protected] · CNA
- 2026-10-21 1 new reference · CNA
- 2026-10-24 Affected versions changed · Red Hat
- 2026-10-24 CVSS score added · Red Hat
- 2026-10-30 Fix available: Linux/Linux@1f43b6b099fa39032780b9494cedfd98f318f3c4, Linux/Linux@4e5a6d89083af6f23f0ac2cb611ef267590a3ece, Linux/[email protected] +3 · CNA
- 2026-10-30 3 new references · CNA
- 2026-11-07 Affected versions changed · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/4e5a6d89083af6f23f0ac2cb611ef267590a3ece
- https://git.kernel.org/stable/c/1f43b6b099fa39032780b9494cedfd98f318f3c4
- https://git.kernel.org/stable/c/87f4914758f2da10b56cdb7f90ed815ade1e8ea3
- https://git.kernel.org/stable/c/1d27214fd9a4d2c0c6d998fc9d4fb61448a3438e
- https://git.kernel.org/stable/c/64ac0cb574c740bf723affb79b646eeba920db6b
- https://git.kernel.org/stable/c/c5f91098edee98c015f78488460a0609e62582a5
- https://git.kernel.org/stable/c/4cd378423a33194a773c267fc58606d28fce95cf
- https://git.kernel.org/stable/c/747928b5d4ff8c8de55138a54c13980e4bb88578
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Sources
- CVE-2026-98851 · CVE Program
- CVE-2026-98851 · NVD
- FIRST EPSS
- GHSA-95vh-jxqc-h2w9 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98851 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences