CVE-2026-48053 in Kolibri
Summary
by MITRE • 08/17/2026
Kolibri is an offline-first education platform. Prior to version 0.19.4, several Kolibri API endpoints accept an unvalidated `baseurl` parameter and fetch attacker-controlled URLs from the Kolibri server, reflecting the response body back to the caller. The original report identified two endpoints on the `RemoteFacilityUser*` viewsets; remediation review found two further reflection points on the same pattern. The GET endpoint was unauthenticated. Version 0.19.4 fixes the vulnerability.
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Analysis
by VulDB Data Team • 08/17/2026
The Kolibri education platform, designed as an offline-first solution for learning in low-resource environments, contains a critical server-side request forgery and open redirect vulnerability affecting versions prior to 0.19.4. This security flaw stems from improper input validation within specific API endpoints that handle facility user management operations. The core technical deficiency lies in the acceptance of an unvalidated `baseurl` parameter by these endpoints. When this parameter is supplied, the server constructs a URL based on attacker-controlled input and subsequently issues an HTTP request to fetch content from that external source. Crucially, instead of merely using the fetched data for internal processing or validation purposes as intended, the application reflects the response body directly back to the original caller. This behavior transforms what might initially appear as a standard server-side request forgery into a mechanism capable of exfiltrating sensitive information or facilitating further attacks depending on the target URL's content and authentication state.
The vulnerability is present across multiple endpoints within the `RemoteFacilityUser` viewsets, which are responsible for managing user data in distributed Kolibri deployments where facilities may sync with remote servers. The original security report identified two such vulnerable endpoints, but subsequent remediation reviews revealed that at least two additional endpoints share this same flawed pattern of accepting and reflecting unvalidated URLs. This indicates a systemic issue within the API design rather than an isolated coding error. One of these affected endpoints is accessible via GET requests without requiring any form of authentication. The lack of access control on this specific endpoint significantly lowers the barrier for exploitation, allowing any internet-connected actor to trigger the server-side request and receive the response data from arbitrary destinations controlled by the attacker.
From a technical perspective, this vulnerability aligns with CWE-918 Server-Side Request Forgery (SSRF), specifically involving the reflection of server responses back to the client. It also exhibits characteristics of CWE-601 URL Redirection to Untrusted Site, although the primary impact here is data exfiltration via response reflection rather than simple browser redirection. In terms of offensive security frameworks, this behavior maps to MITRE ATT&CK technique T1557, which covers Adversary-in-the-Middle scenarios where an attacker can intercept or manipulate communications between clients and servers by leveraging the server's trust in its own network requests. The ability to fetch arbitrary URLs allows attackers to probe internal networks if the Kolibri server has access to private IP ranges, potentially leading to further compromise of infrastructure behind firewalls that would otherwise be inaccessible from the public internet.
The operational impact of this vulnerability is severe due to the potential for data leakage and reconnaissance. An attacker can use the unauthenticated GET endpoint to make the Kolibri server fetch URLs pointing to internal services such as database administration interfaces, cloud metadata endpoints (like AWS EC2 instance metadata), or other sensitive internal APIs. By analyzing the reflected response body, an attacker may extract authentication tokens, configuration details, private keys, or other proprietary data stored on these internal resources. Furthermore, if the fetched content includes user-specific information from a remote facility server that is accessible to the Kolibri instance, it could lead to unauthorized access to student and teacher records, violating privacy regulations such as GDPR or FERPA depending on the jurisdiction. The reflection of arbitrary response bodies also opens the door for cross-site scripting attacks if the reflected content contains executable scripts that are then rendered in a web context where user interaction occurs.
To mitigate this vulnerability, organizations running Kolibri versions prior to 0.19.4 must upgrade immediately to version 0.19.4 or later, which implements proper validation and sanitization of the `baseurl` parameter. Until an upgrade is feasible, administrators should consider implementing network-level controls such as firewall rules that restrict outbound HTTP/HTTPS traffic from the Kolibri server to only known trusted domains. Additionally, deploying a Web Application Firewall with SSRF detection capabilities can help block requests attempting to access internal IP ranges or suspicious external hosts. It is also advisable to review API gateway configurations to ensure that sensitive endpoints are not exposed without appropriate authentication mechanisms where possible, although upgrading remains the definitive fix for this code-level flaw.