CVE-2025-53990 Overview
CVE-2025-53990 is a PHP Object Injection vulnerability in the JetFormBuilder WordPress plugin by Jetmonsters. The flaw stems from deserialization of untrusted data [CWE-502] and affects all versions up to and including 3.5.1.2. Attackers with high-privilege access can inject crafted serialized PHP objects that trigger malicious behavior during unserialization. Successful exploitation can lead to remote code execution, file manipulation, or full site compromise when a suitable POP (Property-Oriented Programming) chain is present in the WordPress environment.
Critical Impact
Authenticated attackers can deliver malicious serialized payloads to JetFormBuilder, potentially achieving arbitrary code execution and full compromise of confidentiality, integrity, and availability on the affected WordPress site.
Affected Products
- JetFormBuilder WordPress plugin versions through 3.5.1.2
- WordPress sites running JetFormBuilder by Jetmonsters
- Hosting environments where vulnerable JetFormBuilder versions are installed
Discovery Timeline
- 2025-07-16 - CVE-2025-53990 published to NVD
- 2026-04-23 - Last updated in NVD database
Technical Details for CVE-2025-53990
Vulnerability Analysis
The vulnerability is an insecure deserialization issue classified under [CWE-502]. JetFormBuilder passes attacker-controllable input to a PHP unserialize() operation without sufficient validation. When PHP unserializes attacker-supplied data, it instantiates objects and invokes magic methods such as __wakeup(), __destruct(), and __toString(). Combined with reachable classes in WordPress core, plugins, or themes, this behavior enables POP chain construction.
A successful exploit can pivot to file read, file write, SQL execution, or remote code execution depending on the gadget chain available in the target environment. The CWE-502 classification places this issue in the same category as object injection flaws historically used to fully compromise WordPress installations.
Root Cause
The root cause is the unsafe deserialization of user-supplied input within JetFormBuilder request handling. The plugin accepts serialized data and processes it through unserialize() without enforcing a strict allow-list of classes or using safe parsing alternatives such as JSON. This allows arbitrary PHP object instantiation during request processing.
Attack Vector
Exploitation occurs over the network against a WordPress site running a vulnerable JetFormBuilder version. The attacker requires high privileges on the WordPress site to reach the vulnerable code path. Once authenticated with the required role, the attacker submits a crafted serialized PHP payload to a JetFormBuilder endpoint. The payload triggers a POP chain that executes during deserialization, yielding code execution or other malicious effects.
No verified proof-of-concept exploit code is publicly available. See the Patchstack advisory for JetFormBuilder for additional technical context.
Detection Methods for CVE-2025-53990
Indicators of Compromise
- HTTP POST requests to JetFormBuilder endpoints containing serialized PHP markers such as O:, a:, or s: followed by class names and length specifiers.
- Unexpected PHP file creation or modification under wp-content/uploads/, wp-content/plugins/, or theme directories after JetFormBuilder requests.
- New or unknown administrative WordPress users created shortly after form submissions.
- Outbound network connections initiated from the WordPress PHP-FPM or web server process to attacker-controlled hosts.
Detection Strategies
- Inspect web server access logs for requests to JetFormBuilder AJAX or REST endpoints carrying base64 or serialized payload signatures.
- Apply WAF rules that flag PHP serialization patterns in form submissions, focusing on the O:<digits>: object marker.
- Audit PHP error logs for unexpected class instantiation failures or __wakeup/__destruct execution errors tied to the plugin.
Monitoring Recommendations
- Monitor administrative role assignments and configuration changes in the WordPress database.
- Track integrity of plugin and theme files using file integrity monitoring on the WordPress installation directory.
- Alert on PHP processes spawning shell utilities such as sh, bash, curl, or wget on hosts running WordPress.
How to Mitigate CVE-2025-53990
Immediate Actions Required
- Update JetFormBuilder to a version newer than 3.5.1.2 as soon as the vendor releases a patched release.
- Audit WordPress user accounts and revoke any high-privilege roles not strictly required.
- Review web server and WordPress logs for serialized payload patterns dating back to plugin installation.
- Rotate WordPress administrative credentials and API keys if compromise is suspected.
Patch Information
Refer to the Patchstack advisory for JetFormBuilder for the fixed version and upgrade instructions. Apply the vendor-supplied update through the WordPress plugin manager or via WP-CLI.
Workarounds
- Disable or remove JetFormBuilder until a patched version is installed.
- Restrict access to JetFormBuilder endpoints using web server access controls or a WAF rule blocking serialized PHP payloads.
- Limit high-privilege WordPress accounts and enforce multi-factor authentication for administrators and editors.
# Update JetFormBuilder using WP-CLI once a patched version is available
wp plugin update jetformbuilder --version=<patched_version>
# Or temporarily deactivate the plugin until patching is possible
wp plugin deactivate jetformbuilder
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
