CVE-2026-19596

MEDIUMPre-NVD 5.95.9—
EchelonGraph scoreHIGH confidence

Score 5.9 from GitHub Security Advisory published 2026-09-10. a secondary CVSS source baseline 5.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

An XML External Entity (XXE) vulnerability exists in the XML collector of multiple versions of OpenNMS Meridian and Horizon. When OpenNMS collects XML from a source whose response is attacker-controlled (for example a compromised monitored host or an HTTP man-in-the-middle position), the collector's XML parser resolves external entities and external DTDs. This allows an attacker to read files accessible to the OpenNMS service account, including database credentials, and to induce out-of-band requests.

The solution is to upgrade to Meridian 2024.3.13, 2025.0.10 and Horizon 36.0.4 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.

CVSS v3
5.9
EG Score
5.9(high)
EG Risk
27(Track)
EG Risk 27/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity59% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
12%
KEV
Not listed

Published

September 10, 2026

Last Modified

September 18, 2026

Advisory Details (1)

Auto-updated Sep 10, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr.
github_pr

NMS-20206: Fix XXE in XML collector

Fix merged in OpenNMS/opennms PR #8782 on 2026-08-21 — awaiting tagged release

https://github.com/OpenNMS/opennms/pull/8782

Vendor Advisories for CVE-2026-19596(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 16× in last 7d / 29× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-20 20:43 UTCEG score recompute
  2. 2026-09-20 20:43 UTCGHSA enrichment
  3. 2026-09-19 20:06 UTCEG score recompute
  4. 2026-09-19 20:06 UTCGHSA enrichment
  5. 2026-09-18 19:30 UTCEG score recompute
  6. 2026-09-18 19:30 UTCGHSA enrichment
  7. 2026-09-18 19:27 UTCEPSS rescore
  8. 2026-09-18 01:34 UTCEG score recompute
  9. 2026-09-18 01:34 UTCGHSA enrichment
  10. 2026-09-17 00:58 UTCEG score recompute
  11. 2026-09-17 00:58 UTCGHSA enrichment
  12. 2026-09-16 14:07 UTCEPSS rescore
  13. 2026-09-16 05:14 UTCEPSS rescore
  14. 2026-09-16 00:22 UTCEG score recompute
  15. 2026-09-16 00:21 UTCGHSA enrichment
  16. 2026-09-14 23:43 UTCGHSA enrichment
  17. 2026-09-13 23:07 UTCEG score recompute
  18. 2026-09-13 23:07 UTCGHSA enrichment
  19. 2026-09-13 16:46 UTCEPSS rescore
  20. 2026-09-12 22:31 UTCEG score recompute
  21. 2026-09-12 22:31 UTCGHSA enrichment
  22. 2026-09-12 15:00 UTCEPSS rescore
  23. 2026-09-11 21:55 UTCEG score recompute
  24. 2026-09-11 21:55 UTCGHSA enrichment
  25. 2026-09-11 14:52 UTCEPSS rescore
Show 4 more
  1. 2026-09-10 21:19 UTCEG score recompute
  2. 2026-09-10 20:30 UTCEG score recompute
  3. 2026-09-10 20:25 UTCEG score recompute
  4. 2026-09-10 20:24 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-19596?
CVE-2026-19596 is a medium vulnerability published on September 10, 2026. An XML External Entity (XXE) vulnerability exists in the XML collector of multiple versions of OpenNMS Meridian and Horizon. When OpenNMS collects XML from a source whose response is attacker-controlled (for example a compromised monitored host or an HTTP man-in-the-middle position), the…
When was CVE-2026-19596 disclosed?
CVE-2026-19596 was first published in the National Vulnerability Database on September 10, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-19596 actively exploited?
CVE-2026-19596 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 88.3% of all scored CVEs.
What is the CVSS score of CVE-2026-19596?
CVE-2026-19596 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-19596?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-19596, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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