CVE-2026-23231
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix use-after-free in nf_tables_addchain() nf_tables_addchain() publishes the chain to table->chains via list_add_tail_rcu() (in nft_chain_add()) before…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.79%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix use-after-free in nf_tables_addchain() nf_tables_addchain() publishes the chain to table->chains via list_add_tail_rcu() (in nft_chain_add()) before registering hooks. If nf_tables_register_hook() then fails, the error path calls nft_chain_del() (list_del_rcu()) followed by nf_tables_chain_destroy() with no RCU grace period in between. This creates two use-after-free conditions: 1) Control-plane: nf_tables_dump_chains() traverses table->chains under rcu_read_lock(). A concurrent dump can still be walking the chain when the error path frees it. 2) Packet path: for NFPROTO_INET, nf_register_net_hook() briefly installs the IPv4 hook before IPv6 registration fails. Packets entering nft_do_chain() via the transient IPv4 hook can still be dereferencing chain->blob_gen_X when the error path frees the chain. Add synchronize_rcu() between nft_chain_del() and the chain destroy so that all RCU readers -- both dump threads and in-flight packet evaluation -- have finished before the chain is freed.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.79% probability · 54th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/2a6586ecfa4ce1413daaafee250d2590e05f1a33Patch
- https://git.kernel.org/stable/c/2f9a4ffeb763aec822f8ff3d1e82202d27d46d4bPatch
- https://git.kernel.org/stable/c/7017745068a9068904e1e7a1b170a5785647cc81Patch
- https://git.kernel.org/stable/c/71e99ee20fc3f662555118cf1159443250647533Patch
- https://git.kernel.org/stable/c/dbd0af8083dd201f07c49110b2ee93710abdff28Patch
- https://git.kernel.org/stable/c/f3fe58ce37926a10115ede527d59b91bcc05400aPatch
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://cert-portal.siemens.com/productcert/html/ssa-253495.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.