CVE-2026-63233 in Koollab LMS
Summary
by MITRE • 07/29/2026
A SQL injection and unsafe deserialisation vulnerability in Koollab LMS allowed an authenticated attacker to inject through the assessment overall answer endpoint, control data passed to unserialize(), write a webshell to a publicly accessible location, and execute arbitrary code on the server.
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Analysis
by VulDB Data Team • 07/29/2026
The vulnerability identified in Koollab LMS represents a critical security flaw that combines SQL injection and unsafe deserialization techniques to enable remote code execution. This vulnerability exists within the assessment overall answer endpoint, which serves as an entry point for authenticated attackers to exploit multiple layers of security weaknesses. The combination of these vulnerabilities creates a particularly dangerous attack vector where an adversary can leverage a single authenticated session to gain full server control. The SQL injection component allows attackers to manipulate database queries through the assessment endpoint, while the unsafe deserialization flaw enables arbitrary code execution by controlling data passed to the unserialize() function.
The technical implementation of this vulnerability follows a specific exploitation pattern that aligns with common attack methodologies documented in the ATT&CK framework under technique T1059.007 for command and script injection. The attacker first establishes an authenticated session within the Learning Management System, then targets the assessment overall answer endpoint which appears to accept user input without proper sanitization. When the vulnerable endpoint processes the input, it passes manipulated data through a unserialize() function call, creating an unsafe deserialization condition that allows attackers to execute malicious code on the target server. This exploitation path directly relates to CWE-502 which categorizes unsafe deserialization as a critical weakness in software systems.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass full system compromise and potential data breaches. Once an attacker successfully executes arbitrary code, they can establish persistent access through webshell deployment, potentially leading to data exfiltration, lateral movement within network infrastructure, and establishment of command and control channels. The fact that the webshell can be written to a publicly accessible location indicates that the vulnerability allows for direct server manipulation without requiring additional attack vectors or privilege escalation techniques. This makes the exploitation particularly dangerous as it provides attackers with immediate access to the underlying operating system and its resources.
Mitigation strategies for this vulnerability require immediate implementation of multiple defensive measures including input validation, parameterized queries, and secure deserialization practices. Organizations should implement proper sanitization of all user inputs, especially those processed through endpoints like assessment overall answer, to prevent SQL injection attacks. The use of prepared statements and parameterized queries is essential to neutralize SQL injection risks at the database interaction level. Additionally, the application must eliminate unsafe deserialization patterns by avoiding direct unserialization of user-controllable data or implementing strict input validation before any deserialization operations occur. Network segmentation and access controls should be implemented to limit the potential impact of successful exploitation, while regular security audits and penetration testing can help identify similar vulnerabilities in other system components. The vulnerability demonstrates the critical importance of following secure coding practices as outlined in OWASP Top Ten and NIST cybersecurity guidelines to prevent such dangerous combinations of flaws that can lead to complete system compromise.