Linux: Use After Free
CVE-2025-39951 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 14c231959a16ca41bfdcaede72483362a8c645d7, 5e94e44c9cb30d7a383d8ac227f24a8c9326b770, aaf900a83508c8cd5cdf765e7749f9076196ec7f 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 0.15% 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 14c231959a16ca41bfdcaede72483362a8c645d7 or 5e94e44c9cb30d7a383d8ac227f24a8c9326b770 or aaf900a83508c8cd5cdf765e7749f9076196ec7f or 4f364023ddcfe83f7073b973a9cb98584b7f2a46, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.245 or 5.15.194 or 6.1.154 or 6.6.108, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 04e5b1fb01834a602acaae2276b67a783a8c6159 up to, but not including, 14c231959a16ca41bfdcaede72483362a8c645d7; 04e5b1fb01834a602acaae2276b67a783a8c6159 up to, but not including, 5e94e44c9cb30d7a383d8ac227f24a8c9326b770; 04e5b1fb01834a602acaae2276b67a783a8c6159 up to, but not including, aaf900a83508c8cd5cdf765e7749f9076196ec7f; 04e5b1fb01834a602acaae2276b67a783a8c6159 up to, but not including, 4f364023ddcfe83f7073b973a9cb98584b7f2a46; 04e5b1fb01834a602acaae2276b67a783a8c6159 up to, but not including, 00e98b5a69034b251bb36dc6e7123d7648e218e4; 04e5b1fb01834a602acaae2276b67a783a8c6159 up to, but not including, c2ff91255e0157b356cff115d8dc3eeb5162edf2; 04e5b1fb01834a602acaae2276b67a783a8c6159 up to, but not including, 7ebf70cf181651fe3f2e44e95e7e5073d594c9c0; 5.5 | 14c231959a16ca41bfdcaede72483362a8c645d7, 5e94e44c9cb30d7a383d8ac227f24a8c9326b770, aaf900a83508c8cd5cdf765e7749f9076196ec7f, 4f364023ddcfe83f7073b973a9cb98584b7f2a46, 00e98b5a69034b251bb36dc6e7123d7648e218e4, c2ff91255e0157b356cff115d8dc3eeb5162edf2 |
| Linux | Linux Kernel | 5.5 up to, but not including, 5.10.245; 5.11 up to, but not including, 5.15.194; 5.16 up to, but not including, 6.1.154; 6.2 up to, but not including, 6.6.108; 6.7 up to, but not including, 6.12.49; 6.13 up to, but not including, 6.16.9; 6.17 | 5.10.245, 5.15.194, 6.1.154, 6.6.108, 6.12.49, 6.16.9 |
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: um: virtio_uml: Fix use-after-free after put_device in probe When register_virtio_device() fails in virtio_uml_probe(), the code sets vu_dev->registered = 1 even though the device was not successfully registered. This can lead to use-after-free or other issues.
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
- git.kernel.org/stable/c/00e98b5a69034b251bb36dc6e7123d7648e218e4
- git.kernel.org/stable/c/14c231959a16ca41bfdcaede72483362a8c645d7
- git.kernel.org/stable/c/4f364023ddcfe83f7073b973a9cb98584b7f2a46
- git.kernel.org/stable/c/5e94e44c9cb30d7a383d8ac227f24a8c9326b770
- git.kernel.org/stable/c/7ebf70cf181651fe3f2e44e95e7e5073d594c9c0
- git.kernel.org/stable/c/aaf900a83508c8cd5cdf765e7749f9076196ec7f
- git.kernel.org/stable/c/c2ff91255e0157b356cff115d8dc3eeb5162edf2
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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