CVE-2019-20903 in Atlaskit
Summary
by MITRE • 10/04/2020
The hyperlinks functionality in atlaskit/editor-core in before version 113.1.5 allows remote attackers to inject arbitrary HTML or JavaScript via a Cross-Site Scripting (XSS) vulnerability in link targets.
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Analysis
by VulDB Data Team • 11/15/2020
The vulnerability identified as CVE-2019-20903 resides within the hyperlinks functionality of atlassian's editor-core component, specifically affecting versions prior to 113.1.5. This issue represents a critical cross-site scripting vulnerability that enables remote attackers to execute malicious code within the context of a victim's browser session. The flaw manifests when the editor processes link targets that contain malicious HTML or JavaScript content, bypassing normal input validation mechanisms that should prevent such injections. The vulnerability stems from insufficient sanitization of user-provided link targets, allowing attackers to craft malicious URLs that, when clicked, execute arbitrary code in the victim's browser environment.
The technical exploitation of this vulnerability follows the classic XSS attack pattern where an attacker crafts a malicious hyperlink containing script tags or other HTML elements within the link target parameter. When a user interacts with such a crafted link within the editor environment, the malicious content gets executed without proper context isolation or sanitization. This behavior aligns with CWE-79, which describes cross-site scripting vulnerabilities where untrusted data is directly included in web pages without proper validation or encoding. The vulnerability operates at the application layer and specifically affects web-based rich text editing interfaces that process user-generated content, making it particularly dangerous in collaborative environments where multiple users interact with shared documents.
The operational impact of this vulnerability extends beyond simple code execution, as it can lead to complete session hijacking, data theft, and privilege escalation within the affected application. An attacker could potentially steal user credentials, modify content, or redirect users to malicious sites that appear legitimate within the trusted application environment. This vulnerability particularly affects Atlassian products that utilize the editor-core component, including Confluence and Jira, where users might inadvertently click on malicious links in shared documentation or issue tracking systems. The attack vector is particularly insidious because it can be concealed within seemingly legitimate hyperlinks, making it difficult for users to identify malicious content until after exploitation has occurred.
Mitigation strategies for CVE-2019-20903 primarily involve upgrading to version 113.1.5 or later of the atlassian/editor-core component, which implements proper HTML sanitization and input validation for link targets. Organizations should also implement comprehensive content security policies that restrict the execution of inline scripts and limit the sources from which hyperlinks can be loaded. The implementation of strict input validation and output encoding practices, as recommended by OWASP and the ATT&CK framework, should be enforced across all web applications that process user-generated content. Additionally, regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other components of the application stack, particularly those handling rich text editing and user input processing functions.