CVE-2017-8812 in MediaWiki
Summary
by MITRE
MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2 allows remote attackers to inject > (greater than) characters via the id attribute of a headline.
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Analysis
by VulDB Data Team • 01/23/2021
MediaWiki versions prior to 1.27.4, 1.28.x prior to 1.28.3, and 1.29.x prior to 1.29.2 contain a vulnerability that enables remote attackers to inject greater than characters through the id attribute of a headline element. This flaw represents a classic cross-site scripting vulnerability that exploits improper input validation and sanitization mechanisms within the wiki rendering engine. The vulnerability specifically affects the parsing and processing of headline elements where the id attribute is not properly escaped or validated before being rendered in the final HTML output. Attackers can leverage this weakness by crafting malicious wiki markup that includes specially formatted headline elements containing unescaped greater than characters, which can then be executed in the context of a victim's browser when the affected page is rendered. This vulnerability falls under CWE-79 Improper Neutralization of Input During Web Page Generation, which is a fundamental web application security weakness that allows attackers to inject malicious code into web pages viewed by other users. The attack vector operates through the standard wiki editing interface where users can create or modify pages containing headline elements with id attributes, making it particularly dangerous in collaborative environments where multiple users contribute content. The operational impact of this vulnerability extends beyond simple XSS exploitation as it can serve as a stepping stone for more sophisticated attacks, including session hijacking, credential theft, or redirection to malicious sites. According to ATT&CK framework, this vulnerability maps to T1203 Exploitation for Client Execution and T1566 Phishing, as it enables attackers to deliver malicious payloads through compromised wiki content that users might trust due to the legitimate appearance of the wiki interface. The vulnerability is particularly concerning in enterprise and educational environments where MediaWiki serves as a primary collaboration platform, as it can be exploited to compromise user sessions and potentially gain access to sensitive institutional information. The affected versions demonstrate a lack of proper input sanitization for HTML attributes, specifically failing to escape special characters that have semantic meaning in HTML parsing. This oversight creates a scenario where attackers can inject arbitrary HTML or JavaScript code that executes in the context of other users' browsers, potentially allowing for full compromise of user sessions and data exfiltration. The remediation process requires updating to the patched versions of MediaWiki, which implement proper HTML attribute escaping and input validation for headline id attributes, ensuring that special characters are properly encoded before rendering. Organizations should also implement additional security measures such as content security policies and regular security audits of wiki content to prevent exploitation of similar vulnerabilities in other parts of their web applications.