Linux: Use After Free
CVE-2026-43084 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 22730cb96093b5be0609063bbb1923dbecd61252, 41e3652a178cb0eecd48e0e6e27fbb73a004046a, 9e5ebef91120d2764aefe557c3a484b6288f341f 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 0.13% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 22730cb96093b5be0609063bbb1923dbecd61252 or 41e3652a178cb0eecd48e0e6e27fbb73a004046a or 9e5ebef91120d2764aefe557c3a484b6288f341f or 936206e3f6ff411581e615e930263d6f8b78df9d, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.83 or 6.18.24 or 6.19.14, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 371de2bef6582a3f58049b3d18e190924af9c9a0 up to, but not including, 22730cb96093b5be0609063bbb1923dbecd61252; 870e3e63da8e88daffe9d692a025c711658018a8 up to, but not including, 41e3652a178cb0eecd48e0e6e27fbb73a004046a; 70e2e3ce4f6841e12ec1c104fc76c0e707398ec4 up to, but not including, 9e5ebef91120d2764aefe557c3a484b6288f341f; e19079adcd26a25d7d3e586b1837493361fdf8b6 up to, but not including, 936206e3f6ff411581e615e930263d6f8b78df9d; 6.12.75 up to, but not including, 6.12.83; 6.18.14 up to, but not including, 6.18.24; 6.19.4 up to, but not including, 6.19.14 | 22730cb96093b5be0609063bbb1923dbecd61252, 41e3652a178cb0eecd48e0e6e27fbb73a004046a, 9e5ebef91120d2764aefe557c3a484b6288f341f, 936206e3f6ff411581e615e930263d6f8b78df9d, 6.12.83, 6.18.24 |
| Linux | Linux Kernel | 6.12.75 up to, but not including, 6.12.83; 6.18.14 up to, but not including, 6.18.24; 6.19.4 up to, but not including, 6.19.14 | 6.12.83, 6.18.24, 6.19.14 |
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 CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nfnetlink_queue: make hash table per queue Sharing a global hash table among all queues is tempting, but it can cause crash: BUG: KASAN: slab-use-after-free in nfqnl_recv_verdict+0x11ac/0x15e0 [nfnetlink_queue] [..] nfqnl_recv_verdict+0x11ac/0x15e0 [nfnetlink_queue] nfnetlink_rcv_msg+0x46a/0x930 kmem_cache_alloc_node_noprof+0x11e/0x450 struct nf_queue_entry is freed via kfree, but parallel cpu can still encounter such an nf_queue_entry when walking the list. Alternative fix is to free the nf_queue_entry via kfree_rcu() instead, but as we have to alloc/free for each skb this will cause more mem pressure.
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
Recent Use After Free vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 8.3 High severity
- 8.8 High severity
- 8.8 High severity
- 8.3 High severity
Spotted an error? Tell us.