CVE-2026-62018 in Gunslinger Plugin
Summary
by MITRE • 10/29/2026
Unauthenticated PHP Object Injection in Gunslinger <= 1.11 versions.
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Analysis
by VulDB Data Team • 10/29/2026
The vulnerability identified as an unauthenticated PHP object injection flaw within the Gunslinger application, specifically affecting versions up to and including 1.11, represents a critical security risk that stems from improper handling of user-supplied input during the deserialization process. This type of vulnerability occurs when an application accepts serialized data from an external source without adequate validation or sanitization before passing it to PHP's unserialize function. In this specific context, attackers can craft malicious payloads containing arbitrary PHP objects with pre-defined magic methods such as __wakeup(), __destruct(), or __toString(). When the vulnerable script processes these inputs, it instantiates these objects and executes their associated methods, effectively allowing an unauthenticated attacker to achieve remote code execution on the target server. The absence of authentication requirements significantly lowers the barrier for exploitation, enabling any internet user with network access to initiate attacks without needing valid credentials or prior interaction with the application's legitimate features.
From a technical perspective, this flaw aligns directly with Common Weakness Enumeration identifier CWE-502, which describes Deserialization of Untrusted Data. The core issue lies in the assumption that serialized data originates from a trusted source within the same execution context. However, when user input is injected into the serialization stream, an attacker can manipulate object properties to point to existing classes or libraries available on the server. By leveraging gadget chains—sequences of methods across different classes that perform dangerous operations such as file system access, command execution via functions like exec() or shell_exec(), or database manipulation—the attacker gains a high degree of control over the application's runtime environment. This mechanism bypasses traditional input validation checks because the data is not treated as plain text but rather interpreted as executable object structures by the PHP engine.
The operational impact of this vulnerability is severe, potentially leading to complete compromise of the underlying system hosting the Gunslinger software. Successful exploitation allows an attacker to read sensitive configuration files containing database credentials or API keys, modify application logic to bypass security controls, install web shells for persistent access, and pivot into internal network segments if the server has broader connectivity. In many cases, this can result in data exfiltration of user information stored by the platform, integrity violations where content is altered maliciously, and availability issues through resource exhaustion or system crashes caused by malformed object states. The unauthenticated nature means that automated scanning tools and opportunistic attackers can exploit this flaw at scale across vulnerable instances deployed on public-facing servers without any prior reconnaissance requiring login credentials.
Mitigation strategies must focus immediately on updating the Gunslinger software to a version later than 1.11 where this deserialization issue has been patched by developers through stricter input validation or removal of unsafe unserialize calls in favor of safer alternatives like JSON decoding for data exchange formats that do not support arbitrary object instantiation. If an immediate update is not feasible, administrators should implement strict allowlists for any classes permitted during unserialization using PHP's spl_autoload_register and custom handlers to restrict which objects can be instantiated. Additionally, deploying a Web Application Firewall with rules capable of detecting serialized payload patterns containing dangerous magic methods or known gadget chain signatures can provide a layer of defense in depth. It is also critical to ensure that the server environment does not expose unnecessary classes or libraries that could serve as part of an attack vector, thereby reducing the potential impact even if exploitation attempts are made against other components within the application stack.