CVE-2016-6556: OpenNMS Stored XSS via SNMP Agent Data

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-09-24 · updated 2026-06-17
Weakness: CWE-79

Description

OpenNMS version 18.0.1 and prior are vulnerable to a stored XSS issue due to insufficient filtering of SNMP agent supplied data. By creating a malicious SNMP 'sysName' or 'sysContact' response, an attacker can store an XSS payload which will trigger when a user of the web UI views the data. This issue was fixed in version 18.0.2, released on September 20, 2016.

Affected products

OpenNMS: before 18.0.2-1 — fixed in 18.0.2-1

How to fix

Upgrade to a fixed version: OpenNMS 18.0.2-1. Check the vendor advisory for mitigations.

References

https://github.com/OpenNMS/opennms/pull/1019
https://www.rapid7.com/blog/post/2016/11/15/r7-2016-24-opennms-stored-xss-via-snmp-cve-2016-6555-cve-2016-6556/
https://github.com/OpenNMS/opennms/pull/1019
https://www.rapid7.com/blog/post/2016/11/15/r7-2016-24-opennms-stored-xss-via-snmp-cve-2016-6555-cve-2016-6556/

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