Linux: Use After Free
CVE-2026-23231 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 2a6586ecfa4ce1413daaafee250d2590e05f1a33, 7017745068a9068904e1e7a1b170a5785647cc81, f3fe58ce37926a10115ede527d59b91bcc05400a as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.04% chance of exploitation within 30 days, higher than 65% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 2a6586ecfa4ce1413daaafee250d2590e05f1a33 or 7017745068a9068904e1e7a1b170a5785647cc81 or f3fe58ce37926a10115ede527d59b91bcc05400a or dbd0af8083dd201f07c49110b2ee93710abdff28, whichever matches your release line, or a later version.
- Update RUGGEDCOM RST2428P (6GK6242-6PA00) to V4.0 or a later version.
- Update Linux Kernel to 6.1.165 or 6.6.128 or 6.12.75 or 6.18.14, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 91c7b38dc9f0de4f7f444b796d14476bc12df7bc up to, but not including, 2a6586ecfa4ce1413daaafee250d2590e05f1a33; 91c7b38dc9f0de4f7f444b796d14476bc12df7bc up to, but not including, 7017745068a9068904e1e7a1b170a5785647cc81; 91c7b38dc9f0de4f7f444b796d14476bc12df7bc up to, but not including, f3fe58ce37926a10115ede527d59b91bcc05400a; 91c7b38dc9f0de4f7f444b796d14476bc12df7bc up to, but not including, dbd0af8083dd201f07c49110b2ee93710abdff28; 91c7b38dc9f0de4f7f444b796d14476bc12df7bc up to, but not including, 2f9a4ffeb763aec822f8ff3d1e82202d27d46d4b; 91c7b38dc9f0de4f7f444b796d14476bc12df7bc up to, but not including, 71e99ee20fc3f662555118cf1159443250647533; 3.16 | 2a6586ecfa4ce1413daaafee250d2590e05f1a33, 7017745068a9068904e1e7a1b170a5785647cc81, f3fe58ce37926a10115ede527d59b91bcc05400a, dbd0af8083dd201f07c49110b2ee93710abdff28, 2f9a4ffeb763aec822f8ff3d1e82202d27d46d4b, 71e99ee20fc3f662555118cf1159443250647533 |
| Siemens | RUGGEDCOM RST2428P (6GK6242-6PA00) | before V4.0 | V4.0 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | all versions | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 3.16 up to, but not including, 6.1.165; 6.2 up to, but not including, 6.6.128; 6.7 up to, but not including, 6.12.75; 6.13 up to, but not including, 6.18.14; 6.19 up to, but not including, 6.19.4 | 6.1.165, 6.6.128, 6.12.75, 6.18.14, 6.19.4 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/2a6586ecfa4ce1413daaafee250d2590e05f1a33
- git.kernel.org/stable/c/2f9a4ffeb763aec822f8ff3d1e82202d27d46d4b
- git.kernel.org/stable/c/7017745068a9068904e1e7a1b170a5785647cc81
- git.kernel.org/stable/c/71e99ee20fc3f662555118cf1159443250647533
- git.kernel.org/stable/c/dbd0af8083dd201f07c49110b2ee93710abdff28
- git.kernel.org/stable/c/f3fe58ce37926a10115ede527d59b91bcc05400a
Other references
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
Spotted an error? Tell us.