Linux: Use After Free
CVE-2025-39861 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 bd75eba88e88d7b896b0c737b02a74a12afc235f, 1503756fffe76d5aea2371a4b8dee20c3577bcfd, 7cc08f2f127b9a66f46ea918e34353811a7cb378 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 0.16% 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 bd75eba88e88d7b896b0c737b02a74a12afc235f or 1503756fffe76d5aea2371a4b8dee20c3577bcfd or 7cc08f2f127b9a66f46ea918e34353811a7cb378 or 28010791193a4503f054e8d69a950ef815deb539, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.105 or 6.12.46 or 6.16.6, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | ab4e4380d4e158486e595013a2635190e07e28ce up to, but not including, bd75eba88e88d7b896b0c737b02a74a12afc235f; ab4e4380d4e158486e595013a2635190e07e28ce up to, but not including, 1503756fffe76d5aea2371a4b8dee20c3577bcfd; ab4e4380d4e158486e595013a2635190e07e28ce up to, but not including, 7cc08f2f127b9a66f46ea918e34353811a7cb378; ab4e4380d4e158486e595013a2635190e07e28ce up to, but not including, 28010791193a4503f054e8d69a950ef815deb539; 6.4 | bd75eba88e88d7b896b0c737b02a74a12afc235f, 1503756fffe76d5aea2371a4b8dee20c3577bcfd, 7cc08f2f127b9a66f46ea918e34353811a7cb378, 28010791193a4503f054e8d69a950ef815deb539 |
| Linux | Linux Kernel | 6.4 up to, but not including, 6.6.105; 6.7 up to, but not including, 6.12.46; 6.13 up to, but not including, 6.16.6; 6.17 | 6.6.105, 6.12.46, 6.16.6 |
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 | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: vhci: Prevent use-after-free by removing debugfs files early Move the creation of debugfs files into a dedicated function, and ensure they are explicitly removed during vhci_release(), before associated data structures are freed. Previously, debugfs files such as "force_suspend", "force_wakeup", and others were created under hdev->debugfs but not removed in vhci_release(). Since vhci_release() frees the backing vhci_data structure, any access to these files after release would result in use-after-free errors. Although hdev->debugfs is later freed in hci_release_dev(), user can access files after vhci_data is freed but before hdev->debugfs is released.
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
- 7.8 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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