CVE-2026-23231: Linux kernel · netfilter: nf_tables: fix use-after-free in nf_tables_addchain()
Affects Linux kernelSource GCVE Database
Public exploit available (Exploit-DB) · CVSS 7.8 High · fixed in 6.8.0-1053.56~22.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 1.0% chance of exploitation in 30 days – higher than 63% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-1053.56~22.04.1, 6.8.0-1059.65~22.04.1, 6.8.0-1058.65~22.04.1 +42
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 4 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by kernel.org
, 50 days before disclosure
CVE published
on cve.org
, t = 0
First Exploit-DB entry (opens in a new tab)
Linux nf_tables 6.19.3 - Local Privilege Escalation
, 61 days after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-8244-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8245-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8254-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8257-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8258-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8260-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8261-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8254-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8254-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8440-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8508-1 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
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.
References
- ubuntu.com/security/CVE-2026-23231 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23231 (opens in a new tab)
- git.kernel.org/linus/71e99ee20fc3f662555118cf1159443250647533 (opens in a new tab)
- git.kernel.org/stable/c/2a6586ecfa4ce1413daaafee250d2590e05f1a33 (opens in a new tab)
- git.kernel.org/stable/c/2f9a4ffeb763aec822f8ff3d1e82202d27d46d4b (opens in a new tab)
- git.kernel.org/stable/c/7017745068a9068904e1e7a1b170a5785647cc81 (opens in a new tab)
- git.kernel.org/stable/c/71e99ee20fc3f662555118cf1159443250647533 (opens in a new tab)
- git.kernel.org/stable/c/dbd0af8083dd201f07c49110b2ee93710abdff28 (opens in a new tab)
- git.kernel.org/stable/c/f3fe58ce37926a10115ede527d59b91bcc05400a (opens in a new tab)
- ubuntu.com/security/notices/USN-8244-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8245-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8254-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8257-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8258-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8260-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8261-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8254-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8254-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8440-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8508-1 (opens in a new tab)