CVE-2026-19182Network attack vector

Alarm-state manipulation via inverted credential guard

Published Aug 13, 2026 · Updated Aug 13, 2026

Incorrect authorization in affected OpenNMS Meridian and Horizon releases allows remote authenticated users to alter alarms via the v2 REST API. The endpoint skips credential verification because a nonblank-username guard is inverted, permitting ROLE_REST users to record changes as any username. Meridian 2024.1.0 through 2024.3.11 and 2025.0.0 through 2025.0.8, and Horizon 36.0.0 through 36.0.2 are affected; ROLE_REST plus ROLE_READONLY still permits acknowledging, escalating, or clearing alarms.

CVSS severity4.3
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in affected OpenNMS Meridian and Horizon releases allows remote authenticated users to alter alarms via the v2 REST API. The endpoint skips credential verification because a nonblank-username guard is inverted, permitting ROLE_REST users to record changes as any username. Meridian 2024.1.0 through 2024.3.11 and 2025.0.0 through 2025.0.8, and Horizon 36.0.0 through 36.0.2 are affected; ROLE_REST plus ROLE_READONLY still permits acknowledging, escalating, or clearing alarms.

The record

CVE
CVE-2026-19182
Published
Aug 13, 2026
Updated
Aug 13, 2026
Vendor
The OpenNMS Group, Inc.
Product
OpenNMS Meridian
Classifications
CWE-863, T1562.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 13, 2026CVE publishedPublication date reported by the CVE source.
  2. 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.

  1. Affected versionversion=2024.1.0 <2024.3.12
  2. Affected versionversion=2025.0.0 <2025.0.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The OpenNMS Group, Inc. · OpenNMS Meridianversion=2024.1.0 <2024.3.12; version=2025.0.0 <2025.0.9
The OpenNMS Group, Inc. · OpenNMS Horizonversion=36.0.0 <36.0.3

Published CVSS scores

4.3The OpenNMS GroupCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1562.001Impair Defenses: Disable or Modify Tools

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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