CVE-2026-54857 in Quirky Plugin
Summary
by MITRE • 10/29/2026
Unauthenticated PHP Object Injection in Quirky <= 1.23 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 Quirky content management system, specifically affecting versions up to and including 1.23, represents a critical security risk that allows attackers to execute arbitrary code on the target server without requiring valid credentials. This type of vulnerability stems from the improper handling of user-supplied input during the deserialization process in PHP applications. When an application accepts data such as cookies, POST parameters, or URL arguments and passes them directly into functions like unserialize() without adequate validation or sanitization, it creates a pathway for malicious actors to inject crafted serialized objects. In the context of Quirky, this flaw likely exists within modules or core components that process user input for administrative tasks or content management features, where the system inadvertently trusts external data structures and attempts to reconstruct PHP objects from them.
The technical mechanism behind this exploitation relies on the ability of an attacker to craft a serialized object containing malicious payloads, often referred to as gadget chains. These gadgets are sequences of existing classes within the application or its dependencies that, when instantiated through deserialization, trigger unintended side effects such as file inclusion, remote code execution, or database manipulation. Because the vulnerability is unauthenticated, the attack surface is significantly expanded; any internet-facing instance of Quirky becomes immediately exploitable by anonymous users. This eliminates the need for brute-force attacks against login pages or credential theft, allowing threat actors to compromise the system with minimal effort and high reliability. The lack of authentication checks means that automated scanning tools can easily detect and exploit this weakness across large segments of the internet, leading to widespread compromises if left unpatched.
The operational impact of successfully exploiting this vulnerability is severe and multifaceted. An attacker who gains control over the PHP execution context effectively achieves full administrative access to the underlying web server environment. This level of compromise enables the exfiltration of sensitive data stored in the database, including user credentials, personal information, and proprietary content. Furthermore, the compromised server can be repurposed as a node in botnets for distributed denial-of-service attacks, used to host phishing sites or malware distribution platforms, or leveraged to pivot into other parts of the internal network infrastructure. The integrity of the Quirky installation is also at risk, as attackers may inject backdoors or modify core files to maintain persistent access even after initial patches are applied if not thoroughly audited.
To mitigate this vulnerability and prevent future occurrences, immediate action must be taken by system administrators and developers. The primary remediation step is to upgrade the Quirky installation to a version newer than 1.23, where the vendor has presumably addressed the insecure deserialization logic or removed the vulnerable code paths entirely. If upgrading is not immediately feasible, temporary mitigations should include implementing strict input validation on all parameters that are passed to serialization functions, ensuring that only expected data types and structures are processed. Additionally, enabling PHP session configuration options such as serialize_handler=php_binary can sometimes reduce risk by making it harder for attackers to predict object structures, although this is not a definitive fix. It is also advisable to restrict file permissions on the web root directory to prevent unauthorized modifications and to deploy Web Application Firewalls that can detect patterns associated with serialized payload injection attempts.
From a classification perspective, this vulnerability aligns closely with CWE-502, which denotes Deserialization of Untrusted Data. This weakness occurs when an application deserializes data from untrusted sources without proper validation or integrity checks. In terms of offensive security frameworks, the exploitation technique maps to MITRE ATT&CK techniques related to Command and Scripting Interpreter execution via PHP objects, often categorized under lateral movement or initial access depending on the specific payload delivered. Understanding these mappings helps in aligning defensive strategies with industry-standard threat models, ensuring that monitoring rules are tuned to detect similar patterns of abuse across other applications within the organization's ecosystem. Regular security audits focusing on input handling and serialization practices are essential to maintain a robust defense posture against such high-severity flaws.