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CVE-2021-39341

49
FAUCET Score

CVE-2021-39341 is a high-severity vulnerability affecting the OptinMonster WordPress plugin, versions up to and including 2.6.4. It allows for sensitive information disclosure and unauthorized setting updates due to insufficient authorization validation in the logged_in_or_has_api_key function, potentially enabling malicious web script injection. With a CVSS score of 8.2 (HIGH) and an EPSS score indicating high exploitability, the vulnerability can be exploited remotely without authentication and with low complexity, leading to high confidentiality impact and low integrity impact. While not listed in CISA's KEV catalog, Nuclei templates exist for detecting this vulnerability, and it has garnered significant community discussion and media coverage, including an article from BleepingComputer.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.6.4CPE matchmatch criteria
cpe:2.3:a:optinmonster:optinmonster:*:*:*:*:*:wordpress:*:*
>= 2.6.4, <= 2.6.4CPE match
cpe:2.3:a:optinmonster:optinmonster:*:*:*:*:*:wordpress:*:*

CVSS Data

CVSS version used by this source: 3.1

8.2HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
4.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
21.93%
Probability of exploitation in next 30 days
EPSS Percentile
97.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
Nuclei: CVE-2021-39341 · Jun 9, 2025
This CVE's current EPSS score of 0.2193 is in the 96th percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

plugins.trac.wordpress.org / browser/optinmonster/trunk/OMAPI/RestApi.php
Third Party Advisory
wordfence.com / vulnerability-advisories
Third Party Advisory
wordfence.com / blog/2021/10/1000000-sites-affected-by-optinmonster-vulnerabilities
ExploitThird Party Advisory