MC4WP: Mailchimp for WordPress <= 4.8.6 — Authenticated (Admin+) Stored Cross-Site Scripting
CVE-2021-36833Published · Updated Action summary
Affected: ≤4.8.6Update to 4.8.7 or newer
All remediation steps- Severity
- Medium5.5
- CVSS
- 5.5CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:NWhat does this vector mean?
AV:NAttack vector- Network
AC:LAttack complexity- Low
PR:HPrivileges required- High
UI:NUser interaction- None
S:CScope- Changed
C:LConfidentiality- Low
I:LIntegrity- Low
A:NAvailability- None
- Weakness
- CWE-79 Cross-Site Scripting
- Required access
- Unknown
- Exploit prediction (EPSS)
- No score
- CISA KEV
- Not listed
On this page8
Am I affected?
MC4WP: Mailchimp for WordPress mailchimp-for-wp
- Affected≤ 4.8.6
- Patched in4.8.7
Update to 4.8.7 or newer.
You are affected if you run ≤ 4.8.6. Version 4.8.7 and later are not affected by this issue.
- Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under MC4WP: Mailchimp for WordPress.
- No admin access? Run a passive check of your site. It reads public files only.
What to do
- Update to version 4.8.7, or a newer patched version
- Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
- Watch MC4WP: Mailchimp for WordPress to get an email when the next vulnerability is published.
Advisory
Source description from Wordfence Intelligence, credited to Asif Nawaz Minhas.
The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Stored Cross-Site Scripting via several parameters in versions up to, and including, 4.8.6 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers with administrative level permissions and above to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.
Exploits & references
Proof-of-concept & detection
No public proof-of-concept or detection template is known for this vulnerability.
Advisories & patches
- Advisorywordfence.com
Related CVEs
More in MC4WP: Mailchimp for WordPress
All 16| Severity | Vulnerability | CVE | Published |
|---|---|---|---|
| Medium5.3 | Missing Authorization ≤4.14.1Update to 4.15.0 | CVE-2026-27356 | |
| Medium6.5 | Unauthenticated Arbitrary Shortcode Execution ≤4.14.0Update to 4.15.0 | CVE-2026-118166 | |
| Medium5.3 | Missing Authorization ≤4.14.0Update to 4.15.0 | CVE-2026-118167 | |
| Medium6.1 | Reflected Cross-Site Scripting via 'data' Dynamic Content Tag ≤4.14.0Update to 4.14.1 | CVE-2026-87917 | |
| Medium6.4 | Authenticated (Author+) Stored Cross-Site Scripting via Form Response Messages ≤4.12.0Update to 4.12.1 | CVE-2026-4561 |
- Medium5.3Missing Authorization
≤4.14.1Update to 4.15.0
- Medium6.5Unauthenticated Arbitrary Shortcode Execution
≤4.14.0Update to 4.15.0
- Medium5.3Missing Authorization
≤4.14.0Update to 4.15.0
- Medium6.1Reflected Cross-Site Scripting via 'data' Dynamic Content Tag
≤4.14.0Update to 4.14.1
- Medium6.4Authenticated (Author+) Stored Cross-Site Scripting via Form Response Messages
≤4.12.0Update to 4.12.1
Same weakness (Cross-Site Scripting)
All Cross-Site Scripting| Severity | Vulnerability | CVE | Published |
|---|---|---|---|
| High7.2 | Unauthenticated Stored Cross-Site Scripting via Comment User-Agent Header | CVE-2026-120688 | |
| Critical9.8 | Unauthenticated Arbitrary File Upload via File Upload via Public Form Submission | CVE-2026-125055 | |
| Critical9.8 | Unauthenticated PHP Object Injection to Remote Code Execution via 'form' Parameter | CVE-2026-119077 | |
| Medium5.3 | Unauthenticated Sensitive Information Exposure in 'search' Parameter | CVE-2026-121518 |
- High7.2Unauthenticated Stored Cross-Site Scripting via Comment User-Agent Header
EZ SQL Reports Shortcode Widget and DB Backup
≤5.25.25Update to 5.26.45
- Critical9.8Unauthenticated Arbitrary File Upload via File Upload via Public Form Submission
Chatterbug Forms – Fast, Flexible WordPress Form Builder
≤1.0.2Update to 1.1
- Critical9.8Unauthenticated PHP Object Injection to Remote Code Execution via 'form' Parameter
ELEX WordPress HelpDesk & Customer Ticketing System
≤3.3.9Update to 3.4.0
- Medium5.3Unauthenticated Sensitive Information Exposure in 'search' Parameter
Customer Reviews for WooCommerce
≤5.127.0Update to 5.128.0
Timeline
CVE published
Severity medium, CVSS 5.5
Record last updated
Sources & licenses
Wordfence record- Vulnerability data
- Wordfence Intelligence. [object Object] Licensed under the CC BY-SA 4.0.
- CVE® identifiers
- [object Object]. Used under the CVE Program. CVE® is a registered trademark of The MITRE Corporation.
- CVSS / CWE
- National Vulnerability Database (NVD), shown unmodified. This product uses the NVD API but is not endorsed or certified by the NVD.
- VulnCrest content
- Summary, remediation guidance and page layout © VulnCrest. Not sourced from NVD.