CVE-2026-98625 netfilter: flowtable: publish HW_DEAD after worker is done
A use-after-free in the Linux kernel netfilter flowtable allows attackers to execute arbitrary code or escalate privileges via race conditions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98625?
CVE-2026-98625 is an use after free vulnerability in Linux, published on 18 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-98625?
How do I fix CVE-2026-98625?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-98625 being exploited?
There is no known exploitation of CVE-2026-98625 in the wild and no public exploit code.
Sources
Also known as AZL-108737, BELL-CVE-2026-98625, DEBIAN-CVE-2026-98625, GHSA-42xw-mjh5-fhf4, UBUNTU-CVE-2026-98625.