How severe is CVE-2020-12760?

CVE-2020-12760 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2020-12760?

CVE-2020-12760 affects the following packages: org.opennms.core:org.opennms.core.daemon (Maven). Ecosystems affected: Maven.

How do I fix CVE-2020-12760?

Update org.opennms.core:org.opennms.core.daemon to 26.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-12760 is resolved across your whole dependency graph.

How do I detect CVE-2020-12760 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.opennms.core:org.opennms.core.daemon, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-12760 if there is no patch (or I can't update yet)?

Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Is CVE-2020-12760 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-12760 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2020-12760?

CVE-2020-12760 has an EPSS (Exploit Prediction Scoring System) score of 3.5%, placing it in the 89th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-12760?

CVE-2020-12760 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2020-12760 published, and has it been updated?

CVE-2020-12760 was published on May 11, 2020 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

HIGH severity

CVE-2020-12760 — org.opennms.core.daemon

HIGHFix: OpenNMS/opennms#2983

CVE-2020-12760 is a high-severity (CVSS 8.8) Deserialization of Untrusted Data vulnerability in org.opennms.core:org.opennms.core.daemon. A fix is available for org.opennms.core:org.opennms.core.daemon — see the affected versions and patch details below.

OpenNMS Horizon RCE via Unsafe Deserialization

Also known asGHSA-853f-x27w-8r74

Published

May 11, 2020

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

3.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs89th percentile — riskier than 89% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

☕org.opennms.core:org.opennms.core.daemon

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

An issue was discovered in OpenNMS Horizon before 26.0.1, and Meridian before 2018.1.19 and 2019 before 2019.1.7. The ActiveMQ channel configuration allowed for arbitrary deserialization of Java objects (aka ActiveMQ Minion payload deserialization), leading to remote code execution for any authenticated channel user regardless of its assigned permissions.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.opennms.core:org.opennms.core.daemon`	all versions	26.0.1`org.opennms.core:org.opennms.core.daemon:26.0.1`

Affected Products

2 products · 3 configurations

Application

opennms horizonopennms

< 26.1.0

range

Application

opennms meridianopennms

≥ 2019 && < 2019.1.7

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.opennms.core:org.opennms.core.daemon, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.opennms.core:org.opennms.core.daemon to 26.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-12760 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2020-12760 in your dependencies?

Find it across Maven, including transitive dependencies.

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