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's process and thread IDs to send any signal to a process they would not normally be permitted to signal, including processes owned by other users or by root. The same check enforces jail boundaries, so a jailed process can signal processes on the host or in other jails. Thread IDs are allocated globally and sequentially, and so can be discovered by brute force with no visibility into the target.
An attacker can stop or terminate arbitrary processes, including critical system daemons, resulting in a Denial of Service (DoS).
References
| Link | Resource |
|---|---|
| https://security.freebsd.org/advisories/FreeBSD-SA-26:25.thr.asc | Vendor Advisory |
Configurations
Configuration 1 (hide)
|
History
26 Jun 2026, 18:58
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://security.freebsd.org/advisories/FreeBSD-SA-26:25.thr.asc - Vendor Advisory | |
| First Time |
Freebsd
Freebsd freebsd |
|
| CPE | cpe:2.3:o:freebsd:freebsd:14.3:-:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:15.1:rc2:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p1:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p12:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p14:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p4:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p10:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:15.0:p9:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:15.0:p1:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p6:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.4:-:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:15.0:p6:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.4:p5:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:15.0:p5:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:15.0:p4:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:15.0:p3:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p13:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p3:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p5:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p9:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p8:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p11:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:15.0:p8:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.4:p2:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.4:p4:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.4:p3:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:15.0:p2:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.4:rc1:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p7:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.3:p2:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:14.4:p1:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:15.0:p7:*:*:*:*:*:* cpe:2.3:o:freebsd:freebsd:15.0:-:*:*:*:*:*:* |
26 Jun 2026, 16:16
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 5.5 |
26 Jun 2026, 15:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-06-26 15:16
Updated : 2026-06-26 18:58
NVD link : CVE-2026-45256
Mitre link : CVE-2026-45256
CVE.ORG link : CVE-2026-45256
JSON object : View
Products Affected
freebsd
- freebsd
CWE
CWE-269
Improper Privilege Management