VULNpocalypse

CVE-2026-54161: upsmon: remote OS command injection (RCE) via attacker-controlled ups.alarm in NOTIFYCMD execution

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-08 00:03 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

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.

Description quoted from the CVE record (assigned by GitHub_M, published 2026-11-03).

Weakness: CWE-78: Improper Neutralization of Special Elements used in an OS Command (‘OS Command Injection’)

How it can be exploited

Exploitable over the network with high attack complexity needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA assessment (SSVC): CISA has no evidence of exploitation. Automatable: no. Technical impact: total.

Public exploit evidence (Exploit Observer)

Exploit Observer found 4 code repositories naming this CVE.

Code repositories that name a CVE are often scanners, copies or fakes, and some are malware. Read the code before running anything.

See all 8 references on Exploit Observer

Live scores

EPSS
0.006
low predicted chance of attack
VEDAS
0.979
strong exploit evidence
On CISA KEV
Not listed
Detection rule
Suricata

Who is affected

ProductAffectedNot affected
networkupstools nutversion >= 2.8.3, <= 2.8.5Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

How to fix it

No fixed version or vendor advisory is listed in the CVE record yet. Watch the vendor’s security page.

How to detect it

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-54161 Network UPS Tools upsmon - OS Command Injection via ups.alarm. Add them to your Suricata rule set and reload.

Show the rules
suricata
alert tcp any 3493 -> $HOME_NET any (msg:"VEDAS CVE-2026-54161 Network UPS Tools upsmon - OS Command Injection via ups.alarm"; flow:established,to_client; content:"ups.alarm"; nocase; fast_pattern; pcre:"/ups\.alarm[^\r\n]*(?:\x60|\x24\x28|\x7c|\x26|\x3b|\x24\x7b)/i"; classtype:attempted-admin; reference:cve,CVE-2026-54161; reference:url,https://www.exploit.observer/?keyword=CVE-2026-54161&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=networkupstools&match=exact; sid:1103403; rev:1;)

CVE-2026-54161.rules on GitHub

References

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.

Supporting partners

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