CVE-2018-19574 in Community Edition
Summary
by MITRE
GitLab CE/EE, versions 7.6 up to 11.x before 11.3.11, 11.4 before 11.4.8, and 11.5 before 11.5.1, are vulnerable to an XSS vulnerability in the OAuth authorization page.
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Analysis
by VulDB Data Team • 06/23/2024
This vulnerability exists in GitLab Community Edition and Enterprise Edition versions ranging from 7.6 through 11.x, specifically affecting releases before 11.3.11, 11.4.8, and 11.5.1 respectively. The issue manifests as a cross-site scripting vulnerability within the OAuth authorization page functionality, representing a critical security flaw that could compromise user sessions and system integrity. The vulnerability stems from inadequate input validation and output encoding mechanisms in the OAuth authorization flow, which processes external authentication requests from third-party applications. This weakness allows attackers to inject malicious scripts into the authorization page through crafted parameters or redirects, potentially enabling session hijacking and unauthorized access to user accounts. The flaw operates under CWE-79 which categorizes cross-site scripting vulnerabilities as weaknesses in input validation and output encoding, making it particularly dangerous in environments where users frequently authenticate through OAuth protocols.
The technical implementation of this vulnerability occurs when GitLab processes OAuth authorization requests and fails to properly sanitize user-supplied input parameters before rendering them in the authorization page context. Attackers can exploit this by crafting malicious OAuth redirect URIs or authorization parameters that contain script payloads. When victims navigate to the affected OAuth authorization page, the malicious code executes within their browser context, potentially stealing session cookies, credentials, or performing unauthorized actions on behalf of the user. The vulnerability is particularly concerning because OAuth authorization pages are trusted interfaces that users expect to be secure, making social engineering aspects more effective. The exploit chain typically involves an attacker registering a malicious application with an OAuth provider, then redirecting users to the vulnerable GitLab instance with crafted parameters that trigger the XSS payload upon page rendering.
The operational impact of this vulnerability extends beyond simple script execution as it can lead to complete account compromise and unauthorized access to sensitive repository data. Attackers can leverage the XSS to steal user session tokens, modify repository permissions, access private code, and potentially escalate privileges within the GitLab instance. The vulnerability affects both individual user accounts and organizational repositories, creating a significant risk for companies relying on GitLab for source code management and collaboration. Organizations may experience data breaches, intellectual property theft, and compliance violations when this vulnerability is exploited in production environments. The widespread use of OAuth authentication in GitLab installations means that a single compromised instance can affect numerous users and applications, amplifying the potential damage. This vulnerability aligns with ATT&CK technique T1566 which covers social engineering through malicious links and redirects, making it particularly dangerous in phishing campaigns targeting developers and security teams.
Mitigation strategies for this vulnerability include immediate patching of affected GitLab versions to the recommended secure releases, implementing proper input validation and output encoding mechanisms throughout the OAuth authorization flow, and conducting thorough security reviews of all authentication-related components. Organizations should also implement additional security controls such as Content Security Policy headers to prevent script execution, monitor authentication logs for suspicious activity, and educate users about the dangers of clicking untrusted links. The fix involves ensuring that all user-supplied parameters are properly sanitized and encoded before being rendered in the OAuth authorization page context, addressing the root cause of the vulnerability. Security teams should also consider implementing web application firewalls to detect and block malicious OAuth parameter patterns, and regularly audit OAuth configurations to prevent unauthorized application registrations that could be used to exploit similar vulnerabilities.