CVE-2026-57813 Overview
CVE-2026-57813 is an Incorrect Privilege Assignment vulnerability [CWE-266] in the MailOptin WordPress plugin developed by properfraction. The flaw affects all versions of MailOptin up to and including 1.2.77.3. Unauthenticated attackers can escalate privileges on WordPress sites running the vulnerable plugin. The vulnerability is exploitable over the network without user interaction and requires no prior authentication. Successful exploitation compromises confidentiality, integrity, and availability of the affected WordPress instance.
Critical Impact
Remote attackers can obtain elevated privileges on WordPress sites running MailOptin <= 1.2.77.3, leading to full site takeover.
Affected Products
- MailOptin WordPress plugin by properfraction
- All versions from n/a through <= 1.2.77.3
- WordPress sites with MailOptin installed and activated
Discovery Timeline
- 2026-07-13 - CVE-2026-57813 published to NVD
- 2026-07-13 - Last updated in NVD database
Technical Details for CVE-2026-57813
Vulnerability Analysis
The vulnerability is categorized as Incorrect Privilege Assignment [CWE-266]. MailOptin assigns privileges to users or requests without adequately verifying the caller's authorization level. This design flaw allows a network attacker to acquire capabilities reserved for higher-privileged roles such as administrators. Because no authentication or user interaction is required, exploitation can be automated at scale against exposed WordPress sites.
The Exploit Prediction Scoring System (EPSS) currently reflects a probability of 0.268% for exploitation activity in the near term. No public proof-of-concept has been released as of the publication date, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.
Root Cause
The root cause is improper enforcement of role and capability checks within MailOptin's request handling logic. The plugin fails to validate whether the requesting user possesses the required WordPress capability before granting access to privileged functionality. As a result, low-privileged or unauthenticated actors receive rights they should not hold.
Attack Vector
An attacker sends crafted HTTP requests to the vulnerable WordPress endpoints exposed by MailOptin. The plugin processes the requests and assigns elevated privileges without validating the caller. The attacker then leverages the acquired privileges to modify site content, create administrative accounts, install malicious plugins, or execute arbitrary code within the WordPress runtime. Technical specifics beyond the advisory summary are not published; refer to the Patchstack WordPress Vulnerability entry for additional context.
Detection Methods for CVE-2026-57813
Indicators of Compromise
- Unexpected creation of WordPress administrator accounts or role changes in wp_users and wp_usermeta tables.
- New or modified plugin and theme files with recent timestamps, particularly PHP files added under wp-content/.
- Anomalous POST or AJAX requests targeting MailOptin endpoints from single or distributed source IPs.
- Outbound connections from the WordPress host to unfamiliar domains following MailOptin request activity.
Detection Strategies
- Inventory WordPress installations and identify sites running MailOptin <= 1.2.77.3 using plugin version scanning.
- Review WordPress audit logs for privilege changes, new administrator accounts, and unauthorized settings modifications.
- Correlate web server access logs against MailOptin URL patterns to identify request bursts from suspicious sources.
Monitoring Recommendations
- Enable a WordPress activity logging plugin to record role assignments, user creation, and plugin installation events.
- Forward web server, PHP-FPM, and WordPress logs to a centralized SIEM for correlation and alerting.
- Alert on any privilege escalation events tied to unauthenticated or low-privileged sessions.
How to Mitigate CVE-2026-57813
Immediate Actions Required
- Update MailOptin to a version later than 1.2.77.3 as soon as the vendor releases a fixed release.
- If no patched version is available, deactivate and remove the MailOptin plugin from affected sites.
- Audit WordPress user accounts and remove any unauthorized administrator or editor accounts.
- Rotate credentials, WordPress secret keys in wp-config.php, and API tokens used by the site.
Patch Information
At the time of publication, review the Patchstack advisory for the latest fixed version and vendor guidance. Apply the patched release across all WordPress instances running MailOptin.
Workarounds
- Restrict access to WordPress admin and MailOptin endpoints using a web application firewall (WAF) with virtual patching rules.
- Block requests to MailOptin AJAX and REST routes from untrusted networks until the plugin is updated or removed.
- Enforce least privilege by reviewing WordPress role capabilities and removing unused administrator accounts.
# Configuration example: disable the MailOptin plugin from WP-CLI until patched
wp plugin deactivate mailoptin
wp plugin delete mailoptin
# Verify no residual MailOptin files remain
find wp-content/plugins -maxdepth 2 -iname 'mailoptin*'
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
