`CVE-2026-19596`

5.9 Medium Protected by RASP

Published 5 days ago. NVD backfills CPE data for days or weeks after publication, and OSV and the exploit indexes lag too. Scope and status here may change.

Description

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.

CWE-611 · XML external entity (XXE)

Exploitation Status

No public exploit

Nothing published shows this CVE being exploited, which is not the same as ruling it out.

CVSS E:U

CISA KEV not listed
CISA Vulnrichment exploitation: none
Indexed PoC none indexed
EPSS 0.21% chance in 30 days

Waratek Defense Posture

Protected by RASP

A Waratek agent blocks this today.

Applicable rule: Promoted to MITIGATED-BY-RASP (security rule): this CVE's weakness (CWE-611: XML External Entity Reference) can be mitigated by an ARMR xxe security rule that blocks this class of attack at the JVM level, without requiring a CVE-specific patch.

Protection full a general security rule for the vulnerability class
Action available security rule
Review automated inferred
Record active

Decided by secure-rule-match : A vulnerability class already blocked by an ARMR security rule

Finding Promoted to MITIGATED-BY-RASP (security rule): this CVE's weakness (CWE-611: XML External Entity Reference) can be mitigated by an ARMR xxe security rule that blocks this class of attack at the JVM level, without requiring a CVE-specific patch.

Candidate fix https://github.com/OpenNMS/opennms/pull/8782 : a pull request: the change under review

Decided by	`secure-rule-match` : A vulnerability class already blocked by an ARMR security rule
Finding	Promoted to MITIGATED-BY-RASP (security rule): this CVE's weakness (CWE-611: XML External Entity Reference) can be mitigated by an ARMR xxe security rule that blocks this class of attack at the JVM level, without requiring a CVE-specific patch.
Candidate fix	https://github.com/OpenNMS/opennms/pull/8782 : a pull request: the change under review

CVSS

5.9 MEDIUM v3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N 1 metric

VRT selects the newest version's highest entry and publishes it as cvssScore, newest rather than largest because scores are not comparable across versions, and highest rather than first because the first entry is frequently a CNA placeholder scoring 0.0 over NVD's own analysis.

Version Score Band Vector Assigner Type

CVSS 3.1 5.9 MEDIUM CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N security@opennms.com Secondary published

Version	Score	Band	Vector	Assigner	Type
CVSS 3.1	5.9	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N`	security@opennms.com	Secondary	published

References

URL	Tags
https://github.com/OpenNMS/opennms/pull/8782	pr

URL

Timeline

Published 2026-09-10 Last modified 2026-09-10

Published	2026-09-10	By the CVE Program.
NVD record modified	2026-09-10	NVD's own last-modified date for this record.

Published

2026-09-10

By the CVE Program.

NVD record modified

2026-09-10

NVD's own last-modified date for this record.

Pipeline policy audit (16 of 21 rules evaluated)

16 of 21 rules ran. The rest were never reached, because an earlier stage settled the CVE, a distinct claim from a rule that ran and found nothing.

# Rule Outcome Status Detail

identity: Does this identifier describe a vulnerability at all? first match wins

1 rejected no-match CVE Program withdrawal of this identifier

scope: Is the vulnerability ARMR's to address? first match wins

2 armr-patch-file no-match An ARMR patch file on disk for this CVE

3 armr-secure-rule-file no-match An ARMR security-rule template on disk for this CVE

4 manual-classification no-match A researcher's recorded decision for this specific CVE

5 manual classification no-match Manual classification of this CVE in the legacy dataset

6 non-java-upstream no-match A root cause in non-Java code: an OS kernel, a C library, or a bundled runtime

7 oracle-component no-match The defect being in a component of a tracked product the agent does not reach: JavaFX, the Java SE installer, the native WebLogic proxy plug-in. Oracle gives these no CPE of their own and names them only in the description.

8 osv-maven no-match An OSV.dev record of this CVE affecting a package published to Maven Central

9 cna-maven-package matched Queued for review CNA declares the affected component is a Maven artifact

10 known-cpe-product not-reached An NVD CPE naming a product ARMR tracks

11 cna-cpe-product not-reached A CPE the CNA published naming a tracked product. Oracle publishes these on advisory day, months before NVD.

12 oracle-advisory-family not-reached A tracked product family named in Oracle's own risk matrix. CPE cannot carry a suite name, only a module.

13 non-deployable-product not-reached The only affected product being a sealed appliance image, where Java runs but no -javaagent can be attached

14 unmatched-product not-reached No tracked product matched above, and none present at all

disposition: What do we do about one that is? cumulative: every rule gets a turn

15 patch-hint matched Mitigation candidate References include candidate fix URL (pr tier): https://github.com/OpenNMS/opennms/pull/8782

16 open-source-maven skipped The affected package being open source on Maven, so the fix can be read

17 poc-derivable skipped An indexed exploit to reverse-engineer, where there is no source to read

18 no-exploit skipped With no fix path, a public exploit, or a CISA record of one

19 secure-rule-match decided it matched Protected by RASP CWE-611 (XML External Entity Reference) is mitigable by an ARMR xxe security rule.

20 below-action-threshold skipped Medium or Low severity, no KEV listing, no PoC clearing the evidence bar, no CISA verdict, no Oracle advisory

21 no-exploit-published skipped A published working exploit for this candidate, not only a proof of concept, a forecast, or nothing at all

Raw stored JSON document for this CVE ↗ · NVD ↗ · CVE.org ↗