CVE-2026-63234 in Koollab
Summary
by MITRE • 07/29/2026
A SQL injection and unsafe deserialisation vulnerability in Koollab LMS allowed an authenticated attacker to inject through the manual mark assessment 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 type of vulnerability falls under the CWE-89 category for SQL injection and CWE-502 for unsafe deserialization, both of which are classified as high-risk issues within the Common Weakness Enumeration framework. The attack vector specifically targets the manual mark assessment endpoint, which serves as an entry point for authenticated users to submit grade data. This particular vulnerability demonstrates how seemingly isolated flaws can compound to create severe security implications when proper input validation and sanitization mechanisms are absent.
The technical exploitation pathway begins with an authenticated attacker leveraging SQL injection capabilities within the manual mark assessment endpoint. This initial compromise allows the attacker to manipulate database queries and extract sensitive information or modify existing records. The more dangerous aspect emerges when the attacker leverages unsafe deserialization practices, specifically targeting the unserialize() function in the application code. The vulnerability enables an attacker to control data passed to this function, which typically processes user-supplied input without adequate validation. When combined with the authenticated access, this creates a perfect storm where malicious payloads can be serialized and then deserialized on the server, effectively bypassing normal security controls.
The operational impact of this vulnerability extends far beyond simple data manipulation or information disclosure. The attacker can write a webshell to a publicly accessible location within the application's directory structure, which fundamentally compromises the entire server environment. This webshell execution capability allows for persistent access and further exploitation of the compromised system. The server-side code execution enables attackers to perform reconnaissance activities, escalate privileges, exfiltrate data, or establish backdoors that can persist even after system restarts. The vulnerability essentially transforms an authenticated user account into a full system compromise mechanism, making it particularly dangerous in environments where user accounts may have elevated privileges.
Mitigation strategies for this vulnerability must address both the SQL injection and unsafe deserialization components simultaneously. Organizations should implement proper input validation and sanitization mechanisms that prevent malicious data from reaching database queries or serialization functions. The use of prepared statements and parameterized queries should be enforced throughout the application to eliminate SQL injection risks. Additionally, unsafe deserialization practices must be eliminated by avoiding direct use of unserialize() with user-controllable data or implementing strict type checking and validation before any deserialization occurs. The principle of least privilege should be applied to limit what authenticated users can do within the system, preventing lateral movement and privilege escalation. Network segmentation and monitoring solutions should be deployed to detect unusual file creation patterns and webshell activity, while regular security audits and penetration testing should be conducted to identify similar vulnerabilities before they can be exploited by malicious actors.
The attack pattern aligns with ATT&CK techniques categorized under T1213 for data from information repositories and T1059 for command and scripting interpreter. The vulnerability demonstrates how attackers can leverage legitimate application features to achieve their objectives, making detection more challenging. Organizations should implement comprehensive logging and monitoring of file system modifications, particularly in publicly accessible directories, as this activity often indicates successful exploitation attempts. The combination of these vulnerabilities also highlights the importance of secure coding practices and regular security training for development teams to prevent such issues from being introduced into applications during the design and implementation phases.