CVE-2026-54161

HighCVSS 8.1

Published: 03/11/2026(UTC)Updated: 03/11/2026(UTC)Translated: 03/11/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Elevated risk

0.64%

51th percentile - higher than 51% of all known CVEs

Summary

In Network UPS Tools 2.8.3 through 2.8.5, upsmon in clients/upsmon.c inserts the server-supplied ups.alarm value into shell commands executed by notify(), async_notify(), and wall(). When a monitored device reports an ALARM state and NOTIFYCMD with EXEC is configured in NOTIFYFLAG ALARM, shell metacharacters in the alarm text are evaluated and can execute arbitrary OS commands as the upsmon account, commonly root.

Risk Assessment

An attacker can achieve command execution with upsmon privileges (often root) via a malicious or compromised upsd, a man-in-the-middle on a plaintext connection, or a compromised UPS device. TLS between upsd and upsmon does not mitigate the compromised-device path.

Recommendation

Upgrade Network UPS Tools to version 2.8.6 or later. Until then, avoid NOTIFYCMD with EXEC for the ALARM flag and restrict network access to upsd.

Other vulnerabilities in Network UPS Tools

CVE-2026-54160High
In Network UPS Tools prior to commits 658b24e and 1aa31d1, the GitHub Actions script used to prepare NUT tarballs and update GitHub Checks statuses and PR comments was mis-structured, mixing code running with higher privileges (single-use token with write permissions) and untrusted inputs (PR source branch). A malicious PR from a fork could extract the GITHUB_TOKEN value, potentially allowing manipulation of repository contents, commit checks/statuses, or PR comments.

Original NVD description (English source)

Network UPS Tools is a collection of programs which provide a common interface for monitoring and administering UPS, PDU and SCD hardware. From 2.8.3 to 2.8.5, upsmon in clients/upsmon.c inserts the server-supplied ups.alarm value into shell commands executed by notify(), async_notify(), and wall(). When a monitored device reports an ALARM state and an operator has configured NOTIFYCMD with EXEC in NOTIFYFLAG ALARM, shell metacharacters in the alarm text are evaluated on POSIX or Windows and can execute arbitrary operating-system commands as the upsmon account, which is commonly root. An attacker can control the value through a malicious or compromised upsd, a man-in-the-middle on a plaintext upsd to upsmon connection, or a compromised UPS device whose driver supplies the alarm upstream of upsd; TLS between upsd and upsmon does not mitigate the compromised-device path. This vulnerability is fixed in 2.8.6.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS