Use After Free in Linux

CVE-2025-39951

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.

Vulnerability class: Use-After-Free

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.002 (3.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 4th percentile — 3.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-39951: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

  • Linux — versions 04e5b1fb01834a602acaae2276b67a783a8c6159, 5.5, 0
  • Linux Kernel — versions 6.17

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-39951?
CVE-2025-39951 is a high-severity vulnerability in Linux, classified under Use After Free. CVSS score: 7.8/10. Published 2025-10-04.
How severe is CVE-2025-39951?
High severity. CVSS v3 base score is 7.8 out of 10.
Is CVE-2025-39951 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.