CVE-2026-102577
Received Received - Intake

SSRF via IPv4-mapped IPv6 in Moodle

Publication date: 2026-09-30

Last updated on: 2026-09-30

Assigner: Fedora Project

Description
A flaw was found in Moodle. Incorrect handling of IPv4-mapped IPv6 addresses within the URL downloader's host-blocking logic allows an authenticated remote user to bypass blocked-host restrictions. By supplying a crafted URL, an attacker can induce the server to make requests to restricted destinations, leading to Server-Side Request Forgery (SSRF).

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Meta Information

Published
2026-09-30
Last Modified
2026-09-30
Generated
2026-09-30
AI Q&A
2026-09-30
EPSS Evaluated
N/A
NVD
CVE-2026-102577
EUVD
EUVD-2026-89716

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
moodle moodle *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-918 The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

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Executive Summary

This vulnerability is in Moodle's URL downloader. It involves incorrect handling of IPv4-mapped IPv6 addresses in the host-blocking logic. An authenticated remote user can bypass blocked-host restrictions by crafting a URL that tricks the server into making requests to restricted destinations. This leads to a Server-Side Request Forgery (SSRF) attack.

Detection Guidance

To detect this vulnerability, monitor Moodle's URL downloader logs for requests to blocked hosts using IPv4-mapped IPv6 addresses. Check for unusual SSRF patterns like requests to internal networks or unintended protocols (file://, gopher://, tftp://).

Commands to inspect logs: grep -r 'downloader' /var/log/moodle/ or journalctl -u apache2 | grep 'URL downloader'. Look for URLs containing '::ffff:' which indicates IPv4-mapped IPv6 addresses.

Impact Analysis

This vulnerability allows an attacker to bypass host-blocking restrictions and induce the server to make requests to restricted destinations. This could enable unauthorized access to internal networks, port scanning, or interaction with unintended protocols like file://, gopher://, or tftp://. It may lead to unauthorized code execution or data exposure.

Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by enabling unauthorized access to internal networks or data through SSRF attacks. If exploited, it may lead to unauthorized data exposure or modification, violating confidentiality and integrity requirements under these regulations.

Mitigation Strategies

Update Moodle to the latest version to patch the IPv4-mapped IPv6 address handling flaw. Temporarily disable the URL downloader feature if an update is not immediately available.

Restrict network access for the Moodle server to prevent SSRF attacks. Monitor and block suspicious outbound requests to internal or restricted destinations.

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