CVE-2019-6970 in Moodle
Summary
by MITRE
Moodle 3.5.x before 3.5.4 allows SSRF.
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Analysis
by VulDB Data Team • 09/08/2025
Moodle version 3.5.x prior to 3.5.4 contains a server-side request forgery vulnerability that enables attackers to make unauthorized requests to internal systems. This vulnerability stems from insufficient validation of URLs in the core application's handling of external resources, allowing malicious actors to bypass normal access controls and potentially gain access to internal network resources or sensitive data. The flaw exists in the application's ability to process and forward requests to arbitrary destinations without proper sanitization or destination verification.
The technical implementation of this vulnerability occurs within Moodle's HTTP request handling mechanisms where external URLs are processed without adequate validation of their destination addresses. Attackers can exploit this by crafting malicious requests that appear to originate from legitimate Moodle processes but actually target internal systems such as databases, administrative interfaces, or other internal services. This type of vulnerability falls under CWE-918, which specifically addresses server-side request forgery conditions where applications fail to validate or sanitize user-supplied URLs or request parameters.
The operational impact of this vulnerability extends beyond simple data exposure, as it can enable attackers to perform reconnaissance on internal network infrastructure, potentially leading to privilege escalation or lateral movement within the network. An attacker could leverage this vulnerability to access internal systems that are normally protected by firewalls or other network security controls, effectively bypassing the application layer security measures. This weakness creates a significant risk for organizations using Moodle for educational or administrative purposes where internal systems may contain sensitive information or critical services.
Organizations should immediately upgrade to Moodle version 3.5.4 or later to remediate this vulnerability, as the patch addresses the core URL validation issues that allowed the SSRF attack vector. Additional mitigations include implementing network-level restrictions that prevent outbound requests to internal addresses, configuring proper firewall rules to limit access to internal systems, and monitoring for unusual outbound traffic patterns. Security teams should also consider implementing web application firewalls that can detect and block suspicious URL patterns that may indicate SSRF attempts. This vulnerability aligns with ATT&CK technique T1071.004, which covers application layer protocol usage for command and control communications, as the SSRF can be used to establish covert communication channels with internal systems.