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CVE-2026-111252— OpenNMS denial of service via XML entity expansion

Quick assessment

Affected
The OpenNMS Group Meridian
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

多个版本的 OpenNMS Meridian 和 Horizon 的 XML 解析中存在拒绝服务（DoS）漏洞。OpenNMS 在解析 XML 时未对实体扩展设置有效限制。包含声明内部实体的 DOCTYPE 的 XML 文档可能会被扩展至极大的大小，从而耗尽服务器内存。具有配置访问权限的身份验证用户可通过需求（requisition）或外部源（foreign-source）导入提供此类文档，其中包括服务器获取并解析的远程需求 URL。无论是深层嵌套的实体，还是被多次引用的单个大型实体，都可能导致内存耗尽。 修复措施

CVSS 6.5 · Medium EPSS 0.25% · P15

Affected Version Matrix 4

VendorProduct Version RangeStatus
The OpenNMS Group Horizon 36.0.0< 36.0.5 affected
The OpenNMS Group Meridian 2024.1.0< 2024.3.14 affected
2025.0.0< 2025.0.11 affected
2026.0.0< 2026.0.1 affected
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I. Basic Information for CVE-2026-111252

Vulnerability Information
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Vulnerability Title
OpenNMS denial of service via XML entity expansion
Source: CVE Program / CVE List V5
Vulnerability Description
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: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
DTD中递归实体索引的不恰当限制(XML实体扩展)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
The OpenNMS Group Meridian 2024.1.0 ~ 2024.3.14 -
The OpenNMS Group Horizon 36.0.0 ~ 36.0.5 -

II. Public POCs for CVE-2026-111252

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III. Intelligence Information for CVE-2026-111252

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Patches & Fixes for CVE-2026-111252 (2)

IV. Related Vulnerabilities

Same product: Meridian
Same vendor: The OpenNMS Group
Same weakness: CWE-776

V. Comments for CVE-2026-111252

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