Description
The official MonsterInsights Pro update distribution bucket (`monster-insights.s3.amazonaws.com`) was compromised. Both the current release (10.2.2) and the version MonsterInsights rolled back to (10.2.0) contain a malicious file, `class-system-check.php`. Three distinct variants were observed on 2026-06-11, all sharing the same AES-256-GCM key, confirming a single threat actor. The attacker retains write access to the S3 bucket and has been actively iterating on the payload throughout the day.
References1
Metrics
- CVSS 3.1
-
10.0
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H - EPSS — exploit probability
- 1% percentile: 45 · as of 12 November 2026
- CWE
- CWE-912
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