Linux: Use After Free
CVE-2026-46036 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 ddf96e23c366c566283fce8377928851fa7f5e81, 7b436ade16cc81095d79b79f8efa3af0a4f5c5a2, 7530f34ec0ca1438d45a75dcb43183a1cc92eced 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 0.14% 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 ddf96e23c366c566283fce8377928851fa7f5e81 or 7b436ade16cc81095d79b79f8efa3af0a4f5c5a2 or 7530f34ec0ca1438d45a75dcb43183a1cc92eced or 670e8864b1a218d72f08db40d0103adf38fa1d9b, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.86 or 6.18.27 or 7.0.4, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 848e447e000c41894ff931dc7c004fd42c8840f8 up to, but not including, ddf96e23c366c566283fce8377928851fa7f5e81; 848e447e000c41894ff931dc7c004fd42c8840f8 up to, but not including, 7b436ade16cc81095d79b79f8efa3af0a4f5c5a2; 848e447e000c41894ff931dc7c004fd42c8840f8 up to, but not including, 7530f34ec0ca1438d45a75dcb43183a1cc92eced; 848e447e000c41894ff931dc7c004fd42c8840f8 up to, but not including, 670e8864b1a218d72f08db40d0103adf38fa1d9b; 6.10 | ddf96e23c366c566283fce8377928851fa7f5e81, 7b436ade16cc81095d79b79f8efa3af0a4f5c5a2, 7530f34ec0ca1438d45a75dcb43183a1cc92eced, 670e8864b1a218d72f08db40d0103adf38fa1d9b |
| Linux | Linux Kernel | 6.10 up to, but not including, 6.12.86; 6.13 up to, but not including, 6.18.27; 6.19 up to, but not including, 7.0.4 | 6.12.86, 6.18.27, 7.0.4 |
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 CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex vfio_cdx_set_msi_trigger() reads vdev->config_msi and operates on the vdev->cdx_irqs array based on its value, but provides no serialization against concurrent VFIO_DEVICE_SET_IRQS ioctls. Two callers can race such that one observes config_msi as set while another clears it and frees cdx_irqs via vfio_cdx_msi_disable(), resulting in a use-after-free of the cdx_irqs array. Add a cdx_irqs_lock mutex to struct vfio_cdx_device and acquire it in vfio_cdx_set_msi_trigger(), which is the single chokepoint through which all updates to config_msi, cdx_irqs, and msi_count flow, covering both the ioctl path and the close-device cleanup path. This keeps the test of config_msi atomic with the subsequent enable, disable, or trigger operations. Drop the pre-call !cdx_irqs test from vfio_cdx_irqs_cleanup() as part of this change: the optimization it provided is redundant with the !config_msi early-return inside vfio_cdx_msi_disable(), and leaving the test in place would be an unsynchronized read of state the new lock is meant to protect.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Use After Free vulnerabilities
- 8.1 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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