CVE-2020-7680 in docsify
Summary
by MITRE
docsify prior to 4.11.4 is susceptible to Cross-site Scripting (XSS). Docsify.js uses fragment identifiers (parameters after # sign) to load resources from server-side .md files. Due to lack of validation here, it is possible to provide external URLs after the /#/ (domain.com/#//attacker.com) and render arbitrary JavaScript/HTML inside docsify page.
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Analysis
by VulDB Data Team • 05/05/2025
The vulnerability identified as CVE-2020-7680 affects docsify versions prior to 4.11.4 and represents a significant cross-site scripting weakness that can be exploited to execute arbitrary code within user browsers. This flaw specifically targets the way docsify.js processes fragment identifiers, which are the parameter components that appear after the hash symbol (#) in URLs. The system's failure to properly validate these fragment identifiers creates an avenue for attackers to manipulate the application's behavior by injecting malicious content directly into the URL structure.
The technical implementation of this vulnerability stems from docsify.js's method of loading content from server-side markdown files using fragment identifiers as the primary mechanism for resource retrieval. When users navigate to URLs containing fragment identifiers, the application processes these components without adequate sanitization or validation checks. This allows attackers to craft malicious URLs such as domain.com/#/attacker.com where the fragment identifier points to an external domain rather than a legitimate markdown file. The vulnerability enables attackers to inject JavaScript or HTML code that gets rendered directly within the docsify page context, bypassing normal security boundaries.
The operational impact of this vulnerability is substantial as it allows attackers to perform various malicious activities including session hijacking, credential theft, and data exfiltration. When exploited, the XSS vulnerability can enable attackers to execute arbitrary JavaScript code within the context of the victim's browser session, potentially leading to complete compromise of user sessions. The vulnerability affects any user who accesses a maliciously crafted URL, making it particularly dangerous in environments where users might encounter such links through phishing campaigns or compromised websites. The attack vector is particularly insidious because it can be delivered through simple URL manipulation without requiring complex exploitation techniques.
Organizations using docsify versions prior to 4.11.4 should immediately implement mitigations including updating to the patched version 4.11.4 or later, which includes proper input validation for fragment identifiers. Additional protective measures include implementing content security policies that restrict the execution of inline scripts and external resource loading, deploying web application firewalls to detect and block malicious fragment identifier patterns, and conducting thorough security reviews of all user-generated content handling mechanisms. This vulnerability aligns with CWE-79, which describes cross-site scripting flaws, and maps to ATT&CK technique T1566 for initial access through malicious links, as well as T1059 for command and control through script injection.
The remediation process requires comprehensive testing of all fragment identifier handling code paths to ensure that proper validation is implemented across all supported browsers and deployment scenarios. Security teams should also monitor for any potential bypass attempts or alternative attack vectors that might exploit similar validation weaknesses in related components. Regular security assessments of documentation systems and static site generators should be conducted to identify and remediate similar vulnerabilities that could affect other components within the application stack. The vulnerability demonstrates the critical importance of input validation in web applications and highlights how seemingly benign URL parsing mechanisms can become attack surfaces when proper sanitization is omitted.