OpenNMS XML collector XXE allows arbitrary file read from the OpenNMS host

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-19596
StatePUBLISHED
AssignerOpenNMS
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-10 21:17:25 UTC
Updated2026-09-10 21:17:25 UTC
DescriptionAn XML External Entity (XXE) vulnerability exists in the XML collector of multiple versions of OpenNMS Meridian and Horizon. When OpenNMS collects XML from a source whose response is attacker-controlled (for example a compromised monitored host or an HTTP man-in-the-middle position), the collector's XML parser resolves external entities and external DTDs. This allows an attacker to read files accessible to the OpenNMS service account, including database credentials, and to induce out-of-band requests. The solution is to upgrade to Meridian 2024.3.13, 2025.0.10 and Horizon 36.0.4 or newer. Meridian and Horizon installation instructions state that they are intended for installation within an organization's private networks and should not be directly accessible from the Internet.

Risk And Classification

Primary CVSS: v3.1 5.9 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Problem Types: CWE-611 | CWE-611 CWE-611 Improper Restriction of XML External Entity Reference

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
3.1CNACVSS5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA The OpenNMS Group Meridian affected 2024.1.0 2024.3.13 maven Not specified
CNA The OpenNMS Group Meridian affected 2025.0.0 2025.0.10 maven Not specified
CNA The OpenNMS Group Horizon affected 36.0.0 36.0.4 maven Not specified

References

ReferenceSourceLinkTags
github.com/OpenNMS/opennms/pull/8782 [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Keith Lee, Foregenix (en)

Additional Advisory Data

Solutions

CNA: Upgrade to Meridian 2024.3.13, 2025.0.10 and Horizon 36.0.4 or newer.

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