by Kastro
Paper/Archive/CVE-2026-11976

CVE-2026-11976

Unknown MonsterInsights Pro — MonsterInsights Pro 10.2.0/10.2.2 - Backdoored via AWS S3 bucket compromise

EPSS 0.5%public exploitCVSS 10.0
critical.is priorityof 100
49
CVSS 10.0 (CNA)10.0 / 10 × 3030.0Not in CISA KEV+300.0EPSS percentile 44.3.443 × 208.9Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
MonsterInsights Pro10.2.0 – < 11.0.011.0.0CNA

Scores by source

WPScan (CNA)10.0CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CISA ADPSSVCExploitation: poc · Automatable: yes · Technical impact: total

References

exploitwpscan.com/vulnerability/d1250410-b919-4a90-8cf2-04031f9e5e2b