---
id: CVE-2026-54161
title: >-
  upsmon: remote OS command injection (RCE) via attacker-controlled ups.alarm in
  NOTIFYCMD execution
summary: >-
  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 s…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-78
vendor: networkupstools
product: nut
affected:
  - 'nut >= 2.8.3, <= 2.8.5'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-11-03T22:36:38.962299Z'
exploitAvailable: true
published: '2026-11-03'
updated: '2026-11-03'
sourceUpdated: '2026-11-03T22:39:49.653Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-54161'
references:
  - url: >-
      https://github.com/networkupstools/nut/security/advisories/GHSA-mjgp-j4gm-6qg5
    label: >-
      https://github.com/networkupstools/nut/security/advisories/GHSA-mjgp-j4gm-6qg5
  - url: 'https://github.com/networkupstools/nut/pull/3499'
    label: 'https://github.com/networkupstools/nut/pull/3499'
  - url: >-
      https://github.com/networkupstools/nut/commit/98e073d4cc31f9c73e2fa0c2677540487d902fe7
    label: >-
      https://github.com/networkupstools/nut/commit/98e073d4cc31f9c73e2fa0c2677540487d902fe7
  - url: >-
      https://github.com/networkupstools/nut/commit/dffba911504866695be698bb5ec49eac40d0f66a
    label: >-
      https://github.com/networkupstools/nut/commit/dffba911504866695be698bb5ec49eac40d0f66a
  - url: >-
      https://github.com/networkupstools/nut/commit/ecf98e7542e4ae2b62b211622ee26989274b2220
    label: >-
      https://github.com/networkupstools/nut/commit/ecf98e7542e4ae2b62b211622ee26989274b2220
tags:
  - cve.org
  - exploit-available
epss: 0.00642
epssPercentile: 0.51012
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/ja-errorpro/CVE-2026-54161'
  checkedAt: '2026-11-07T18:19:00.105Z'
ingestedAt: '2026-11-05T20:33:06.601Z'
---

## Overview

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.

## Affected

- `nut >= 2.8.3, <= 2.8.5`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.