PatchTheCVECVE-2026-45256: When used to deliver a signal to a specific thread, thr_kill2(2) called p_cansignal() to determine whether the
CVE-2026-45256 is a medium-severity flaw (CVSS 5.5) affecting freebsd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
When used to deliver a signal to a specific thread, thr_kill2(2) called p_cansignal() to determine whether the operation was permitted but did not check the result before delivering the signal. The signal was sent even when the permission check failed. The system call returned the resulting error to the caller, but by then the signal had already been delivered. The missing check allows an unprivileged local user who knows or can guess a target
Why this priority
- No elevated risk signals yet
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 5.5 (Medium) |
| Attack vector | Local |
| Attack complexity | Low |
| Privileges needed | Low |
| User interaction | None |
| EPSS exploit chance | 0.1% (top 98%) |
| CISA exploited list | No |
| Weakness | CWE-269 |
| Published | 2026-06-26 |
| Last modified | 2026-06-26 |
Last updated 2026-06-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-45256?
freebsd: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2026-45256 being exploited?
CVE-2026-45256 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-45256 affect?
CVE-2026-45256 affects freebsd. Severity is medium (CVSS 5.5). When used to deliver a signal to a specific thread, thr_kill2(2) called p_cansignal() to determine whether the operation was permitted but did not check the result before delivering the signal. The signal was sent even when the permission
How urgent is CVE-2026-45256?
Priority 20/100. No elevated risk signals yet.
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