Use-after-free in Linux kernel netfilter flowtable hardware offload
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 netfilter flowtable code, from 5.7 onward, sets the HW_DEAD flow state before the offload worker clears its pending bit. A concurrent garbage collection pass can then free the flow while the worker still accesses it, causing a use-after-free.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: publish HW_DEAD after worker is done flow_offload_work_del() sets NF_FLOW_HW_DEAD before the work handler clears NF_FLOW_HW_PENDING. Once a flow is both HW_DYING and HW_DEAD, a concurrent garbage collection pass can remove it and schedule it for RCU freeing. The offload worker holds neither an RCU read lock nor a reference to the flow. If it is preempted after publishing HW_DEAD, the RCU callback can free the flow before the worker resumes and clears HW_PENDING, resulting in a use-after-free. Move HW_DEAD publication to the common worker epilogue after the pending bit is cleared, making it the final flow access by destroy work. Order all preceding flow accesses before publishing the bit that allows garbage collection to free the object.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Upgrade the Linux kernel to 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9 or 7.3. The sources list no fixed version for Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux 10, Red Hat OpenShift Container Platform 4 and Red Hat OpenShift Container Platform 5, and Red Hat lists no fix plan for them.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. 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-2026-98625
- 2026-10-18 Alias added: GHSA-42xw-mjh5-fhf4
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-21 CVSS score added · Red Hat
- 2026-10-30 Affected versions changed · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/f92e8f39726ba68a7c42c6b7566be687c8161579
- https://git.kernel.org/stable/c/00e452a7ca9fda135ea3d04a11128d5088e354a8
- https://git.kernel.org/stable/c/56f39c7d139bb76072efe2fb3dcafc13ba915ad8
- https://git.kernel.org/stable/c/e20701843032c438f879066a77ea85e361c6b999
- https://git.kernel.org/stable/c/b4f0f05dfbe836a171bff261f17d098a4d5461ea
- https://git.kernel.org/stable/c/b0ef9450e93f2adeb77593db14c2ac7c6c8f5060
- https://git.kernel.org/stable/c/f26652e99f519e6bd34f8a9b48fbb33c603585f2
- https://git.kernel.org/stable/c/d644b23afe1ef509c9961a6d84a093c2587edf02
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Sources
- CVE-2026-98625 · CVE Program
- CVE-2026-98625 · NVD
- FIRST EPSS
- GHSA-42xw-mjh5-fhf4 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98625 · 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