CVE-2021-29110 in Portal for ArcGIS
Summary
by MITRE • 10/02/2021
Stored cross-site scripting (XSS) issue in Esri Portal for ArcGIS may allow a remote unauthenticated attacker to pass and store malicious strings in the home application.
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Analysis
by VulDB Data Team • 10/08/2021
The vulnerability identified as CVE-2021-29110 represents a critical stored cross-site scripting flaw within Esri Portal for ArcGIS, a widely deployed geospatial platform used by organizations worldwide for mapping and spatial data management. This vulnerability exists in the application's handling of user input within the home application context, creating a persistent security weakness that can be exploited by remote attackers without requiring authentication credentials. The flaw specifically allows malicious actors to inject and store malicious scripts that will execute in the context of other users who interact with the compromised portal, making it particularly dangerous for enterprise environments where multiple users access shared geospatial resources.
The technical implementation of this vulnerability stems from inadequate input validation and output encoding mechanisms within the Esri Portal for ArcGIS application. When users submit data through various interface components or API endpoints, the system fails to properly sanitize or escape potentially malicious content before storing it in the application's database or configuration files. This stored data is then subsequently rendered to other users without proper security context checks, creating an environment where attacker-controlled JavaScript code can execute in the browsers of legitimate users. The vulnerability manifests when the application processes user-supplied strings that contain script tags or other malicious code constructs, which are then stored and later executed in the context of other users' sessions.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it provides attackers with a persistent foothold within geospatial information systems that often contain sensitive organizational data. Attackers can leverage this vulnerability to execute malicious scripts that can steal session cookies, redirect users to phishing sites, manipulate map data, or even escalate privileges within the portal environment. The unauthenticated nature of the attack means that any user with access to the portal can potentially exploit this vulnerability, making it particularly dangerous for organizations that do not properly segment their geospatial applications or implement additional security controls. Organizations using Esri Portal for ArcGIS may find their spatial data repositories compromised, leading to potential exposure of sensitive mapping information, location-based data, or operational details that could be exploited for further attacks.
Mitigation strategies for CVE-2021-29110 should focus on immediate patch application from Esri, which typically involves implementing proper input validation, output encoding, and content security policy enforcement mechanisms. Organizations should also implement network-level protections including web application firewalls that can detect and block malicious script patterns, and establish monitoring procedures to identify unauthorized modifications to portal content. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and can be mapped to ATT&CK techniques such as T1059.007 for scripting and T1566 for social engineering, as attackers may use the stored XSS to create convincing phishing attacks or manipulate user sessions. Additional defensive measures include implementing strict input sanitization policies, regular security scanning of portal components, and establishing incident response procedures specifically designed to handle stored XSS vulnerabilities in geospatial platforms.