CVE-2022-25636

What it actually does

Heap out-of-bounds write in net/netfilter/nf_dup_netdev.c triggered via nf_tables_offload path allows local privilege escalation to root.

Why it matters to the business

Attackers with local access on affected Linux systems can obtain full root control, enabling data theft, persistence, or lateral movement across servers, appliances, and cloud instances; high ecosystem prevalence increases patch urgency for distributions and vendors.

How an attack unfolds

An attacker with local user access loads malicious nftables rules that invoke the offload code path in nf_dup_netdev, triggering the heap overflow to overwrite kernel structures and execute arbitrary code with elevated privileges; public exploit code exists and the flaw has been referenced in broader Linux kernel exploit trend reports.

How to fix it

Upgrade the Linux kernel to a version containing the fix for the nf_dup_netdev heap write (post 5.6.10 series where applicable); apply vendor-specific updates for Debian, NetApp, Oracle, and other affected distributions; disable unneeded nf_tables offload features where possible until patched.

How to confirm the fix worked

Verify running kernel version is newer than the vulnerable range; confirm nftables offload path is patched by reviewing kernel changelog or source; run regression tests exercising nftables rules on test systems.

Typical attack path

1. Gain local shell access as non-root user
2. Craft and load malicious nftables rules targeting nf_tables_offload
3. Trigger heap out-of-bounds write via netfilter path
4. Overwrite kernel memory to escalate to root
5. Install persistence or exfiltrate data

How to detect it

Review kernel logs for oops or panic messages involving nf_dup_netdev or nf_tables_offload; audit nftables rule additions from untrusted users via auditd or journal logs; search for post-exploitation artifacts such as unexpected root-owned processes or modified kernel modules.

What your security team should do

• Patch all affected Linux kernels immediately given public exploit availability
• Prioritize systems with direct user access or exposed to untrusted local workloads
• Monitor for unusual nftables rule loading in production environments
• Review and restrict nftables usage to least-privilege configurations