OpenNMS denial of service via XML entity expansion

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-111252
StatePUBLISHED
AssignerOpenNMS
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-15 19:17:36 UTC
Updated2026-10-15 19:17:36 UTC
DescriptionA denial of service vulnerability exists in the XML parsing of multiple versions of OpenNMS Meridian and Horizon. OpenNMS parsed XML without an effective limit on entity expansion. A document with a DOCTYPE that declares internal entities can expand to a very large value and exhaust the server memory. An authenticated user with provisioning access can supply such a document through a requisition or foreign-source import, which includes a remote requisition URL that the server fetches and parses. Both deeply nested entities and a single large entity referenced many times cause the memory exhaustion. The fix caps the number of entity expansions for all XML parsing and rejects any DOCTYPE in requisition and foreign-source XML. The solution is to upgrade to Meridian 2024.3.14, 2025.0.11, 2026.0.1 and Horizon 36.0.5 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 6.5 MEDIUM from [email protected]

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

Problem Types: CWE-400 | CWE-776 | CWE-776 CWE-776 Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion') | CWE-400 CWE-400 Uncontrolled Resource Consumption

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA The OpenNMS Group Meridian affected 2024.1.0 2024.3.14 maven Not specified
CNA The OpenNMS Group Meridian affected 2025.0.0 2025.0.11 maven Not specified
CNA The OpenNMS Group Meridian affected 2026.0.0 2026.0.1 maven Not specified
CNA The OpenNMS Group Horizon affected 36.0.0 36.0.5 maven Not specified

References

ReferenceSourceLinkTags
github.com/OpenNMS/opennms/pull/8952 [email protected] github.com
github.com/OpenNMS/opennms/pull/8898 [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: kta1kri (en)

Additional Advisory Data

Solutions

CNA: Upgrade to Meridian 2024.3.14, 2025.0.11, 2026.0.1 and Horizon 36.0.5 or newer.

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