Security readout for executives and security teams
Plain-English summary
Affected OpenNMS Horizon and Meridian releases allow a logged-in high-privilege user to store malicious script in group name or comment fields. If another admin later interacts with that content, the attacker may influence browser behavior or trick the admin into downloading malicious files.
Executive priority
Treat this as a moderate-priority remediation item for OpenNMS environments, especially where monitoring administration is broadly accessible. It is not described as actively exploited, but abuse could target administrators and monitoring trust.
Technical view
CVE-2021-25933 is stored cross-site scripting caused by improper validation in validateFormInput() for groupName and groupComment parameters. It affects OpenNMS Horizon opennms-1-0-stable through 27.1.0-1 and specified Meridian 2015, 2019, and 2020 foundation ranges. CVSS v3.1 is 4.8, CWE-79.
Likely exposure
Exposure is likely limited to organizations running the listed OpenNMS Horizon or Meridian versions with authenticated administrative users able to modify group fields. Internet exposure increases urgency but is not required for exploitation.
Exploitation context
The source bundle does not show CISA KEV listing or confirmed active exploitation. The CVSS vector requires network access, high privileges, and user interaction, so practical abuse depends on compromised or malicious privileged accounts and admin interaction.
Researcher notes
Evidence supports stored XSS in specific group-management parameters, but the bundle does not provide a vendor advisory, fixed version list, or exploitation telemetry. Avoid assuming broader OpenNMS components are affected beyond the named versions and parameters.
Mitigation direction
- Inventory OpenNMS Horizon and Meridian versions against the affected ranges.
- Check OpenNMS vendor guidance for fixed releases containing the referenced commits.
- Upgrade affected systems according to vendor-supported release guidance.
- Restrict administrative access to trusted users and management networks.
- Review group names and comments for suspicious stored content.
- Increase monitoring around privileged OpenNMS account activity.
Validation and detection
- Confirm the installed OpenNMS package and Meridian foundation version.
- Verify whether referenced upstream fixes are present in the deployed codebase.
- Review groupName and groupComment values for unexpected markup or script-like content.
- Check audit logs for recent group administration changes by privileged users.
- Confirm administrative UI access is restricted and monitored.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-25933 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 4.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N1.72.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.8MediumVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/OpenNMS/opennms/commit/eb08b5ed4c5548f3e941a1f0d0363ae4439fa98cCVE reference · x_refsource_MISC
- https://github.com/OpenNMS/opennms/commit/f3ebfa3da5352b4d57f238b54c6db315ad99f10eCVE reference · x_refsource_MISC
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25933CVE reference · x_refsource_MISC
- https://github.com/OpenNMS/opennms/commit/8a97e6869d6e49da18b208c837438ace80049c01%2CCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.