CVE-2026-116391 in GS Logo Slider Plugin
Summary
by MITRE • 10/28/2026
Deserialization of Untrusted Data vulnerability in GS Plugins GS Logo Slider gs-logo-slider allows Object Injection.This issue affects GS Logo Slider: from n/a through 3.8.9.
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Analysis
by VulDB Data Team • 10/28/2026
The identified vulnerability represents a critical security flaw within the GS Logo Slider plugin for WordPress, specifically affecting versions ranging from non-existent initial releases up to version 3.8.9. This issue is classified as an insecure deserialization of untrusted data, which fundamentally allows attackers to perform object injection attacks against the target application. In web development frameworks that utilize PHP or similar languages with robust serialization capabilities, such as WordPress plugins often do, objects are frequently serialized into strings for storage in databases or transmission over networks. When these serialized strings are later converted back into executable objects through deserialization processes, the system assumes the data integrity and origin of the input is trustworthy. However, when this process occurs without adequate validation or sanitization of the incoming data stream, it creates a significant attack vector where malicious actors can manipulate the serialized payload to instantiate arbitrary classes with controlled properties.
The technical mechanism behind this vulnerability relies on PHP's unserialize function or similar deserialization routines that do not strictly enforce type checking or whitelist allowed class names. An attacker who has access to any input field processed by the GS Logo Slider plugin, such as a form submission, URL parameter, or cookie value, can craft a specially constructed serialized object string. By injecting this malicious payload into the application's data flow, the server-side script will deserialize it without verifying its authenticity. This allows the attacker to inject objects of classes that are loaded within the WordPress environment but were not intended for direct instantiation by user input. Through careful selection of these injected classes and their properties, an attacker can trigger specific magic methods such as __wakeup, __destruct, or __toString, which may lead to remote code execution, privilege escalation, or unauthorized access to sensitive system resources depending on the available gadget chains within the WordPress core and other installed plugins.
The operational impact of this vulnerability is severe due to its potential for full server compromise. If an attacker successfully exploits the object injection flaw, they can achieve arbitrary command execution on the web server hosting the vulnerable site. This level of access enables a wide range of malicious activities including defacement of the website, theft of sensitive customer data such as personal identifiable information or financial records, installation of backdoors for persistent access, and use of the compromised server as part of a larger botnet infrastructure. Furthermore, because WordPress plugins often run with the same privileges as the web server process, typically www-data or apache, successful exploitation grants the attacker deep system-level control rather than just limited application-layer permissions. The widespread nature of this plugin means that any site utilizing GS Logo Slider within the affected version range is potentially exposed to these risks without requiring administrative credentials if the input vector is publicly accessible, although some vectors may require authenticated access depending on specific implementation details not fully disclosed in the brief description.
Mitigation strategies must address both immediate remediation and long-term security hygiene. The most effective solution is to upgrade GS Logo Slider to a version greater than 3.8.9 where this vulnerability has been patched by implementing strict input validation, using whitelisting for allowed classes during deserialization, or replacing unsafe serialization functions with safer alternatives like JSON encoding which does not support object instantiation upon decoding. For sites unable to update immediately due to compatibility constraints, temporary mitigations include restricting access to the affected endpoints via web application firewall rules that detect and block known malicious serialized payloads containing PHP class names associated with common gadget chains. Additionally, administrators should enforce principle of least privilege by ensuring the web server process runs with minimal necessary permissions and regularly audit plugin usage to remove any unnecessary components from the production environment.
From a classification perspective, this vulnerability aligns closely with CWE-502 Deserialization of Untrusted Data, which highlights the failure to validate or verify data before deserializing it into an object structure. It also maps to MITRE ATT&CK technique T1190 Exploit Public-Facing Application, as attackers leverage known vulnerabilities in internet-accessible software components to gain initial access. The specific mechanism of injecting objects to trigger unintended behavior falls under the broader category of Insecure Deserialization attacks which are consistently ranked among the most dangerous web application security risks due to their complexity and high impact potential. Organizations must treat this vulnerability with urgency, recognizing that deserialization flaws often bypass traditional input validation checks because they exploit legitimate framework features rather than simple syntax errors or logic bugs in custom code paths.