CVE-2026-54161
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.
Executive briefing
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Evidence confidence: Not assessed Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Technical explanation & impact
Technical root-cause details are not available in the current source record.
Assess the impact using the published CVSS metrics and the affected vendor component.
Affected products and versions
NVD has not supplied machine-readable vulnerable CPE product/version entries for this CVE. This is an information gap, not proof that no products are affected. Check the vendor advisory references below.
Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
No fixed version is displayed unless it is explicitly established by a vendor advisory. Follow the vendor's release notes for exact product and branch applicability.
Vendor advisories, patches & exploit references
- https://github.com/networkupstools/nut/commit/98e073d4cc31f9c73e2fa0c2677540487d902fe7 VENDOR security-advisories@github.com
- https://github.com/networkupstools/nut/commit/dffba911504866695be698bb5ec49eac40d0f66a VENDOR security-advisories@github.com
- https://github.com/networkupstools/nut/commit/ecf98e7542e4ae2b62b211622ee26989274b2220 VENDOR security-advisories@github.com
- https://github.com/networkupstools/nut/pull/3499 VENDOR security-advisories@github.com
- https://github.com/networkupstools/nut/security/advisories/GHSA-mjgp-j4gm-6qg5 VENDOR security-advisories@github.com
- http://www.openwall.com/lists/oss-security/2026/07/01/10 REFERENCE af854a3a-2127-422b-91ae-364da2661108