Privilege escalation in FreeBSD

CVE-2026-45259

sigqueue(2) was marked as permitted in capability mode with the introduction of Capsicum in 2011, but the implementation of kern_sigqueue did not include a capability mode check restricting signal delivery to the calling process's own PID. A process in capability mode can use sigqueue(2) to send signals to any process it could signal following standard Unix permissions, bypassing the Capsicum sandbox restriction. A compromised sandboxed process could interfere with other processes, for example by sending SIGKILL or SIGSTOP. This could be any process running as the same user, or any process, for a superuser sandboxed process.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.001 (2.3th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 2nd percentile — 2.3% 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-2026-45259: held from 0.001 to 0.001.

EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000

Affected products

  • FreeBSD — versions 14.3, 15.0, 14.4-RELEASE

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-45259?
CVE-2026-45259 is a medium-severity vulnerability in FreeBSD, classified under Incorrect Privilege Assignment. CVSS score: 6.5/10. Published 2026-06-27.
How severe is CVE-2026-45259?
Medium severity. CVSS v3 base score is 6.5 out of 10.