CVE-2026-32463 in Sync Post With Other Site Plugin
Summary
by MITRE • 08/18/2026
Contributor Arbitrary File Upload in Sync Post With Other Site <= 1.9.3 versions.
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Analysis
by VulDB Data Team • 08/18/2026
The vulnerability identified as Contributor Arbitrary File Upload in the Sync Post with Other Site plugin, affecting versions up to and including 1.9.3, represents a critical security flaw rooted in insufficient input validation and access control mechanisms within the WordPress ecosystem. This specific weakness allows authenticated users with lower-level privileges, such as contributors or subscribers, to bypass intended restrictions and upload arbitrary files to the server hosting the vulnerable application. The core of this issue lies in how the plugin handles file uploads during synchronization processes between sites. Typically, plugins designed for cross-site content management implement strict checks to ensure that only administrators can modify site configurations or upload media assets that could impact system integrity. However, in version 1.9.3 and earlier releases, these safeguards were either absent or improperly implemented, allowing a malicious actor with even minimal access rights to exploit the file upload functionality for unauthorized purposes.
From a technical perspective, this vulnerability aligns closely with CWE-434, which describes an unrestricted upload of files with dangerous types. In many web applications, including WordPress plugins, there is often a distinction between allowed MIME types and actual file content verification. The flaw in Sync Post with Other Site likely stems from relying solely on client-side validation or server-side extension checks without performing deep packet inspection or magic number analysis to verify the true nature of the uploaded data. Furthermore, it may involve CWE-284, Improper Access Control, where the application fails to enforce proper authorization policies before processing the upload request. An attacker can craft a POST request containing a malicious script, such as a PHP web shell, disguised with an allowed extension like .jpg or .png, or by exploiting MIME type spoofing techniques that trick the server into accepting it as a legitimate image file.
The operational impact of this vulnerability is severe and multifaceted. Once a contributor successfully uploads a malicious file to the wp-content/uploads directory or another writable location accessible via HTTP, they effectively gain the ability to execute arbitrary code on the web server with the privileges of the web service account. This leads directly to CWE-94, Improper Control of Generation of Code (Code Injection), and potentially CWE-78, OS Command Injection if further exploitation steps are taken. The attacker can use this foothold to deface websites, steal sensitive data such as database credentials stored in wp-config.php, install additional malware like backdoors or cryptominers, or pivot into the internal network if the web server is not properly isolated. Given that WordPress powers a significant portion of the internet, compromising even one site through this vector can serve as an entry point for broader campaigns targeting multiple installations using outdated plugin versions.
This attack scenario maps directly to several techniques within the MITRE ATT&CK framework. Specifically, it corresponds to T1505.003, Web Shell: Server Side Script, which involves uploading a script that allows remote command execution. It also relates to T1078, Valid Accounts, as the attacker leverages legitimate but low-privileged credentials obtained through phishing or credential stuffing attacks to perform the upload. The persistence achieved by placing a web shell in an uploads directory ensures long-term access even if initial entry points are patched, making this a critical threat for any organization relying on WordPress-based content management systems.
Mitigation strategies must be implemented immediately to address both the specific vulnerability and broader security hygiene practices. The primary remediation is to update the Sync Post with Other Site plugin to version 1.9.4 or later, where the developers have presumably addressed these access control flaws by enforcing stricter role checks for file upload operations. For organizations unable to patch immediately due to compatibility concerns, temporary mitigations include disabling the specific functionality if not required, restricting write permissions on the wp-content/uploads directory via web server configuration such as .htaccess rules or Nginx configurations to prevent execution of PHP files within that folder, and implementing a Web Application Firewall (WAF) rule set designed to detect and block malicious file uploads based on content signatures rather than just extensions. Additionally, enforcing multi-factor authentication for all administrative accounts reduces the risk of initial credential compromise, while regular security audits and vulnerability scanning can help identify other instances of similar misconfigurations across the infrastructure.