Host file disclosure via external entity resolution
Published Sep 10, 2026 · Updated Sep 10, 2026
XXE in affected OpenNMS Meridian and Horizon releases allows attackers to read host files through attacker-controlled collector responses. The XML collector parser resolves external entities and external DTDs from untrusted response bodies, exposing service-readable files and inducing out-of-band requests. Exploitation requires collection from a compromised monitored host or a man-in-the-middle position; direct access to the OpenNMS web interface is unnecessary.
Summary
What happened
XXE in affected OpenNMS Meridian and Horizon releases allows attackers to read host files through attacker-controlled collector responses. The XML collector parser resolves external entities and external DTDs from untrusted response bodies, exposing service-readable files and inducing out-of-band requests. Exploitation requires collection from a compromised monitored host or a man-in-the-middle position; direct access to the OpenNMS web interface is unnecessary.
The record
- CVE
- CVE-2026-19596
- Published
- Sep 10, 2026
- Updated
- Sep 10, 2026
- Vendor
- The OpenNMS Group, Inc.
- Product
- OpenNMS Meridian
- Classifications
- CWE-611, T1005
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 10, 2026CVE publishedPublication date reported by the CVE source.
- Sep 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=2024.1.0 <2024.3.13
- Affected versionversion=2025.0.0 <2025.0.10
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
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo