Authenticated class loading through JEXL reflection escape
Published Aug 13, 2026 · Updated Aug 13, 2026
Unsafe reflection in OpenNMS Meridian and Horizon allows remote authenticated users to load arbitrary Java classes through the Measurements REST API. OnmsJexlUberspect.getMethod permits crafted JEXL expressions to invoke inherited Class methods on allowed objects, enabling getClass().forName() outside the sandbox allowlist. ROLE_USER access to a network-reachable instance is sufficient; exploitation can expose server data and perform integrity-impacting operations without a reported service interruption.
Summary
What happened
Unsafe reflection in OpenNMS Meridian and Horizon allows remote authenticated users to load arbitrary Java classes through the Measurements REST API. OnmsJexlUberspect.getMethod permits crafted JEXL expressions to invoke inherited Class methods on allowed objects, enabling getClass().forName() outside the sandbox allowlist. ROLE_USER access to a network-reachable instance is sufficient; exploitation can expose server data and perform integrity-impacting operations without a reported service interruption.
The record
- CVE
- CVE-2026-19135
- Published
- Aug 13, 2026
- Updated
- Aug 13, 2026
- Vendor
- The OpenNMS Group, Inc.
- Product
- OpenNMS Meridian
- Classifications
- CWE-470, CAPEC-138, T1210
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 13, 2026CVE publishedPublication date reported by the CVE source.
- Aug 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=2024.1.0 <2024.3.12
- Affected versionversion=2025.0.0 <2025.0.9
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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