Linux: Use After Free
CVE-2026-64424 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 b67625b85c4b1a3725f4be9c6dd8ce3399d11732, 95ecc5b58042f6b6743b589e6588f1cd7ba336aa, a33f37f8d079da7236ed7b7e2aed2a34ab81e7cf 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 b67625b85c4b1a3725f4be9c6dd8ce3399d11732 or 95ecc5b58042f6b6743b589e6588f1cd7ba336aa or a33f37f8d079da7236ed7b7e2aed2a34ab81e7cf or 5ed09a108d93a3b002cc79823d9455b50c4a8be7, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.96 or 6.18.39 or 7.1.4, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 38e6bc185d9544dfad1774b3f8902a0b061aea25 up to, but not including, b67625b85c4b1a3725f4be9c6dd8ce3399d11732; 38e6bc185d9544dfad1774b3f8902a0b061aea25 up to, but not including, 95ecc5b58042f6b6743b589e6588f1cd7ba336aa; 38e6bc185d9544dfad1774b3f8902a0b061aea25 up to, but not including, a33f37f8d079da7236ed7b7e2aed2a34ab81e7cf; 38e6bc185d9544dfad1774b3f8902a0b061aea25 up to, but not including, 5ed09a108d93a3b002cc79823d9455b50c4a8be7; 38e6bc185d9544dfad1774b3f8902a0b061aea25 up to, but not including, 45f1458a85017a023f138b22ac5c76abd477db42; 3.6 | b67625b85c4b1a3725f4be9c6dd8ce3399d11732, 95ecc5b58042f6b6743b589e6588f1cd7ba336aa, a33f37f8d079da7236ed7b7e2aed2a34ab81e7cf, 5ed09a108d93a3b002cc79823d9455b50c4a8be7, 45f1458a85017a023f138b22ac5c76abd477db42 |
| Linux | Linux Kernel | 3.6.1 up to, but not including, 6.12.96; 6.13 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.4; 3.6; 7.2 | 6.12.96, 6.18.39, 7.1.4 |
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.
Official description
In the Linux kernel, the following vulnerability has been resolved: netpoll: fix a use-after-free on shutdown path There is a use-after-free error on netpoll, which is clearly detected by KASAN. BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x3b/0x80 Read of size 1 at addr ... by task kworker/9:1 Workqueue: events queue_process Call Trace: skb_dequeue+0x1e/0xb0 queue_process+0x2c/0x600 process_scheduled_works+0x4b6/0x850 worker_thread+0x414/0x5a0 Allocated by task 242: __netpoll_setup+0x201/0x4a0 netpoll_setup+0x249/0x550 enabled_store+0x32f/0x380 Freed by task 0: kfree+0x1b7/0x540 rcu_core+0x3f8/0x7a0 The problem happens when there is a pending TX worker running in parallel with the cleanup path. This is what happens on netpoll shutdown path: 1) __netpoll_cleanup() is called 2) set dev->npinfo to NULL 3) call_rcu() with rcu_cleanup_netpoll_info() 3.1) rcu_cleanup_netpoll_info() tries to cancel all workers with cancel_delayed_work(), but doesn't wait for the worker to finish 4) and kfree(npinfo); Because 3.1) doesn't really cancel the work, as the comment says "we can't call cancel_delayed_work_sync here, as we are in softirq", the TX worker can run after 4). Tl;DR: queue_process() is not an RCU reader, it reaches npinfo through the work item via container_of(). Use disable_delayed_work_sync() to ensure the worker is completely stopped and prevent any future re-arming attempts. Once npinfo is set to NULL, senders will bail out and not queue new work. The disable flag ensures any in-flight re-arming attempts also fail silently. In the future, we can do the cleanup inline here without needing the npinfo->rcu rcu_head, but that is net-next material.
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: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
Recent Use After Free vulnerabilities
- 9.8 Critical severity
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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