TI-2021-16695 Aliases CVE-2021-39325 GHSA-q4c3-5fjh-5v6h

OptinMonster <= 2.6.0 Reflected Cross-Site Scripting

LOW 29CWE-79Published 2021-09-20 · Updated 2025-03-31

Key facts

Attack vector: Network
Privileges required: None
User interaction: Required
Attack complexity: Low
Impact type: Cross-site scripting
Confidentiality · integrity · availability: Low · Low · None
Fix status: No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-79.

Summary

The OptinMonster WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to insufficient input validation in the load_previews function found in the ~/OMAPI/Output.php file which allows attackers to inject arbitrary web scripts, in versions up to and including 2.6.0.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00905 60th percentileScored 2026-11-07

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
OptinMonster	OptinMonster	2.6.0 – 2.6.0	—	No fix listed	CNA

OptinMonster VendorOptinMonster Affected 2.6.0 – 2.6.0 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:optinmonster:optinmonster::::::wordpress::*	up to 2.6.0	Vulnerable	OptinMonster

cpe:2.3:a:optinmonster:optinmonster:*:*:*:*:*:wordpress:*:* Versions up to 2.6.0 Vulnerable ·OptinMonster

Remediation

No fixed version listed by the sources yet.

Timeline

2026-10-02 Threatist record created from CVE-2021-39325
2026-10-03 Alias added: GHSA-q4c3-5fjh-5v6h

References

Patch 1

https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=2595758%40optinmonster&new=2595758%40optinmonster&sfp_email=&sfph_mail=#file2

Advisory 1

https://www.wordfence.com/vulnerability-advisories/#CVE-2021-39325

TI-2023-00732 Popup Builder by OptinMonster < 2.12.2 - Subscriber+ Arbitrary Post Content Disclosure CVSS 3.1MEDIUM 6.5
TI-2021-16708 OptinMonster <= 2.6.4 Unprotected REST-API Endpoints CVSS 3.1HIGH 8.2
TI-2024-03774 Cross-site scripting in smub Popup Builder & Popup Maker for WordPress – OptinMonster… CVSS 3.1MEDIUM 6.4
TI-2016-09034 The optinmonster plugin before 1.1.4.6 for WordPress has incorrect access control for… CVSS 3.1MEDIUM 5.3

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences