CVE-2026-54858 in Printy Plugin
Summary
by MITRE • 10/29/2026
Unauthenticated PHP Object Injection in Printy <= 1.13.0 versions.
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Analysis
by VulDB Data Team • 10/29/2026
The vulnerability identified as an unauthenticated PHP object injection flaw within Printy versions up to and including 1.13.0 represents a critical security deficiency that allows attackers to execute arbitrary code on the target server without requiring valid credentials. This type of vulnerability arises from the application's failure to properly validate or sanitize user-supplied input before it is passed to functions capable of deserializing PHP objects, such as unserialize(). In many modern web applications, including those built with frameworks like WordPress where Printy operates, serialization is often used for caching sessions, storing complex data structures, or managing plugin states. When an attacker can inject a maliciously crafted serialized string into these processes, they gain the ability to manipulate internal application objects and potentially trigger dangerous magic methods that lead to remote code execution.
The technical root cause lies in the improper handling of input parameters that are directly fed into deserialization routines. In PHP, object injection occurs when user-controlled data is passed to unserialize() without sufficient checks on the class types or properties being instantiated. If the application includes files containing classes with magic methods such as __wakeup(), __destruct(), or __toString(), an attacker can craft a serialized payload that instantiates these specific classes and manipulates their internal state. This manipulation can be leveraged to perform actions unintended by the developer, such as writing arbitrary files to the filesystem, reading sensitive configuration files containing database credentials, or executing system commands through available wrapper functions. The absence of authentication requirements for this vector significantly lowers the barrier to entry for attackers, allowing anyone with network access to exploit the flaw.
From an operational perspective, the impact of this vulnerability is severe and multifaceted. Successful exploitation can lead to a complete compromise of the web server hosting the application. Attackers may use the gained code execution capabilities to install backdoors, deface websites, or pivot into other parts of the internal network if the server has broader access privileges. Furthermore, because Printy deals with image processing and printing services, an attacker might also target specific functionalities related to file uploads or storage paths, potentially leading to data exfiltration of customer images or personal information stored within the application's database. The lack of authentication means that this vulnerability is easily discoverable via automated scanning tools commonly used in reconnaissance phases of cyber attacks, making it a high-priority target for opportunistic attackers and botnets seeking low-hanging fruit.
This flaw aligns with Common Weakness Enumeration (CWE) ID 502, which describes Deserialization of Untrusted Data, and is closely related to CWE 434 regarding the Upload of a Dangerous File if file manipulation capabilities are exploited through object injection. In terms of the MITRE ATT&CK framework, this vulnerability facilitates initial access and potentially privilege escalation depending on the context in which the PHP process runs. It falls under techniques such as T1059 Command and Scripting Interpreter for executing arbitrary code via injected payloads. The unauthenticated nature also relates to improper authentication mechanisms often categorized under CWE 287 or CWE 306, although the primary vector here is specifically the unsafe deserialization practice rather than a failure of login logic itself.
Mitigation strategies must focus on immediate patching and architectural hardening. The most effective remediation is to upgrade Printy to version 1.14.0 or later where this vulnerability has been addressed by developers through input validation and safer serialization practices. If upgrading is not immediately feasible, administrators should implement strict allowlists for deserialization classes if the framework supports it, ensuring that only expected class types can be instantiated during unserialization processes. Additionally, enabling PHP's built-in filter_var with FILTER_UNSAFE_RAW or similar sanitization techniques on all input parameters before they reach any serialization logic can provide a layer of defense. It is also critical to ensure that the web server process runs under a restricted user account with minimal privileges to limit the potential damage if exploitation occurs. Regular security audits and static code analysis tools should be employed to detect unsafe deserialization patterns in custom plugins or themes associated with the application.