A denial of service vulnerability exists in the XML parsing of multiple versions of OpenNMS...
Summary
Vulnerability reported (CVE-2026-111252). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
A 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.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-111252 has been found.
Risk of unauthorized operations or information disclosure. CVSS score: 6.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "CVE-2026-111252" on the vendor's site.
CVE-2026-111252 — CWE-400 / CVSS v3 6.5
Attack vector: remote (network-reachable) / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-400) has been reported.
Check the vendor advisory for the affected versions.
Severity: Medium (CVSS 6.5/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで影響コンポーネントを特定する。
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2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
References
- web nvd.nist.gov
- web security@opennms.com
- web security@opennms.com
- web github.com