CVE-2021-39341 - CVE House
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Status published High CVE-2021-39341

OptinMonster <= 2.6.4 Unprotected REST-API Endpoints

Vulnerability Description

The OptinMonster WordPress plugin is vulnerable to sensitive information disclosure and unauthorized setting updates due to insufficient authorization validation via the logged_in_or_has_api_key function in the ~/OMAPI/RestApi.php file that can used to exploit inject malicious web scripts on sites with the plugin installed. This affects versions up to, and including, 2.6.4.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • Chloe Chamberland, Wordfence

References

More from OptinMonster

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CVE-2021-39325
OptinMonster <= 2.6.0 Reflected Cross-Site Scripting
Medium 6.1

Affected Vendor

OptinMonster

View all reports →

Affected Software

OptinMonster
Vulnerable Versions:
2.6.4

Timeline

Official Publish: November 1st, 2021
Last Modified: March 31st, 2025
Added to House: July 21st, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

Weaknesses (CWE)

CWE-285 CWE-319

MITRE ATT&CK TTPs

T1190 Exploit Public-Facing Application
Initial Access
T1078 Valid Accounts
Persistence
T1548 Abuse Elevation Control Mechanism
Privilege Escalation
T1021 Remote Services
Lateral Movement
T1098 Account Manipulation
Defense Evasion
T1040 Network Sniffing
Collection
T1557 Adversary-in-the-Middle
Credential Access
T1552 Unsecured Credentials
Credential Access
T1071 Application Layer Protocol
Command and Control