CVE-2026-63858 netfilter: nf_tables: add hook transactions for device deletions
A race condition in Linux kernel netfilter hook deletion can disrupt RCU-protected list readers, potentially causing system instability or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-63858?
CVE-2026-63858 is a high-severity vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_tables: add hook transactions for device deletions
Restore the flag that indicates that the hook is going away, ie. NFT_HOOK_REMOVE, but add a new transaction object to track deletion of hooks without altering the basechain/flowtable hook_list during the preparation phase.
The existing approach that moves the hook from the basechain/flowtable hook_list to transaction hook_list breaks netlink dump path readers of this RCU-protected list.
It should be possible use an array for nft_trans_hook to store the deleted hooks to compact the representation but I am not expecting many hook object, specially now that wildcard support for devices is in place.
Note that the nft_trans_chain_hooks() list contains a list of struct nft_trans_hook objects for DELCHAIN and DELFLOWTABLE commands, while this list stores struct nft_hook objects for NEWCHAIN and NEWFLOWTABLE. Note that new commands can be updated to use nft_trans_hook for consistency.
This patch also adapts the event notification path to deal with the list of hook transactions.
Weakness: CWE-362
Which versions are affected by CVE-2026-63858?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-63858?
Apply the vendor's patch.
Is CVE-2026-63858 being exploited?
There is no known exploitation of CVE-2026-63858 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-92582, BELL-CVE-2026-63858, DEBIAN-CVE-2026-63858, GHSA-w348-qxhm-w5rx, ROOT-OS-DEBIAN-11-CVE-2026-63858, ROOT-OS-DEBIAN-12-CVE-2026-63858 and 3 more.