Strategic Overview
- Status
- Unpatched
- Affected Theme
- Grand Conference | Event WordPress
- Affected Version
<= 5.2- CVSS
- 9.8Critical
- Weakness type
- CWE-502 · Deserialization of Untrusted Data
- CVE
CVE-2025-39354
At a glance
CVE-2025-39354 is a critical-severity Deserialization of Untrusted Data vulnerability in the Grand Conference WordPress theme, affecting versions <= 5.2. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. No fixed release has been reported yet; treat installations running this software as exposed. Disclosed April 2025, reported by Bonds.
Vulnerability Overview
The Grand Conference plugin for WordPress is vulnerable to PHP Object Injection in versions up to, and including, 5.2 via deserialization of untrusted input. This makes it possible for unauthenticated attackers to inject a PHP Object. No known POP chain is present in the vulnerable software. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.
CWE-502: Deserialization of Untrusted Data
Reaching this weakness in Grand Conference <= 5.2 takes no account at all. Deserialization of untrusted data means the application reconstructs objects from input a caller controls, letting the attacker choose which classes get instantiated and what their properties hold.
A workable chain turns deserialization into file writes, deletions or code execution, depending on what the loaded classes do in their magic methods. No fixed build of this theme is recorded for Grand Conference yet, so installs running <= 5.2 stay exposed until the vendor ships one.
Remediation
No known patch available. Please review the vulnerability's details in depth and employ mitigations based on your organization's risk tolerance. It may be best to uninstall the affected software and find a replacement.
How does WordSec protect against this?
Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. No patched version is recorded yet, which is the case where a filtering layer matters most, because there is nothing to update to.
- Firewall
- Scanner
- Login Security
External References
Related records
Other vulnerabilities in Grand Conference | Event WordPress
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