CVE-2026-101161 in Ultimate Review Plugin
Summary
by MITRE • 10/03/2026
The WP Ultimate Review WordPress plugin before 2.4.4 does not prevent unauthenticated users from storing crafted review content that makes the reviewed page fail with a fatal error on every subsequent visit, resulting in a persistent denial of service when the WP Ultimate Review WordPress plugin before 2.4.4's review display settings have never been saved.
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Analysis
by VulDB Data Team • 10/03/2026
The vulnerability identified within versions of the WP Ultimate Review plugin prior to release 2.4.4 represents a critical failure in input validation and state management that leads to persistent denial of service conditions for WordPress sites utilizing this functionality. The core issue stems from an insufficient access control mechanism combined with inadequate sanitization of user-supplied data during the review submission process. Specifically, the application fails to enforce authentication requirements on endpoints responsible for storing new reviews, allowing unauthenticated actors to inject maliciously crafted content into the database without any form of verification or privilege escalation. This lack of restriction is particularly dangerous in environments where public-facing forms are enabled, as it permits anyone with network access to interact directly with the review storage logic.
The technical flaw manifests when an attacker submits a specifically constructed payload designed to trigger a fatal error within the PHP execution environment upon subsequent rendering attempts. The vulnerability is contingent on a specific configuration state: the issue only occurs if the plugin's review display settings have never been explicitly saved by an administrator. In this uninitialized or default state, the code path responsible for displaying reviews lacks robust exception handling and type checking for unexpected data structures introduced by the crafted input. When such malformed content is stored in the database, it corrupts the expected schema of the review object. Consequently, every time a visitor loads a page containing these reviews, the PHP interpreter encounters an unrecoverable error during the rendering phase, causing the entire page to crash with a fatal exception rather than displaying the intended content or gracefully handling the bad data.
From an operational perspective, this vulnerability results in a persistent and difficult-to-mitigate denial of service condition for website administrators. Unlike transient errors that might be cleared by refreshing a cache or restarting a server process, this issue is stored persistently within the WordPress database. Once the malicious review content is injected, it remains active until manually deleted from the database via phpMyAdmin or similar tools. This means that even after updating the plugin to version 2.4.4 or later, if the corrupted data is not purged, the site may continue to experience fatal errors on affected pages because the underlying code flaw in older versions has already introduced invalid state into the system. The impact extends beyond simple downtime; it degrades user trust and can negatively affect search engine rankings due to increased bounce rates caused by broken page loads.
This vulnerability aligns with Common Weakness Enumeration (CWE) categories such as CWE-284, which describes Improper Access Control, specifically regarding the failure to enforce authentication on sensitive operations. Furthermore, it relates closely to CWE-756: Missing or Incorrect Explanation of Expected Behavior, where the system fails to handle unexpected input states gracefully, leading to a crash rather than an error message or safe fallback. In terms of the MITRE ATT&CK framework, this activity falls under T1498: Network Denial of Service, as it involves actions intended to disrupt the availability of networked resources by exploiting software vulnerabilities to cause service outages. The persistence aspect also touches upon aspects of data corruption that can hinder recovery efforts if not properly monitored.
To mitigate this risk and prevent recurrence, immediate action is required for sites running affected versions. Administrators must upgrade the WP Ultimate Review plugin to version 2.4.4 or any subsequent release where these access controls and input validations have been corrected. However, upgrading alone is insufficient due to the persistent nature of the stored payload. It is imperative that database administrators manually inspect the wp_wu_reviews table (or equivalent depending on custom prefixes) for entries containing suspiciously malformed content indicative of this exploit vector and delete them before or immediately after applying the patch. Additionally, implementing Web Application Firewall rules can help filter out known malicious patterns associated with this specific injection technique at the network perimeter layer, providing an additional defense-in-depth measure while internal remediation is underway. Regular auditing of plugin configurations to ensure all settings are explicitly saved by authorized users also reduces the window of exposure for similar state-dependent vulnerabilities in other plugins.