CVE-2026-50095 in ArcGIS Server
Summary
by MITRE • 10/26/2026
There is a stored cross site scripting issue in Esri ArcGIS Server 11.1 and earlier on Windows and Linux that in some configurations allows a remote unauthenticated attacker to store files that contain malicious code that may execute in the context of a victim’s browser. A patch is provided for ArcGIS Server software in General Availability and Extended support status, which includes versions 12.1, 12.0, 11.5, 11.3, and 11.1. Other versions are in mature or retired status, which are not patch eligible. Users working with unlisted versions are advised to upgrade and apply the patch.
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Analysis
by VulDB Data Team • 10/26/2026
The vulnerability identified involves a stored cross-site scripting flaw within Esri ArcGIS Server software, affecting versions 11.1 and earlier across both Windows and Linux operating systems. This security defect allows remote unauthenticated attackers to inject malicious scripts into the application by storing files that contain executable code. Unlike reflected XSS attacks where the payload is delivered via a link or request parameter, this stored variant persists on the server side, meaning the malicious content remains available for execution every time an affected page or feature is accessed by users with valid credentials. The core technical flaw lies in insufficient input validation and sanitization mechanisms when processing uploaded files or user-supplied data that gets rendered back to clients without proper encoding. This oversight enables attackers to bypass standard browser security models, such as the same-origin policy, allowing their scripts to run within the trusted context of the ArcGIS Server web interface.
The operational impact of this vulnerability is significant due to its potential for widespread compromise among authenticated users. Since the attack does not require authentication from the attacker's perspective, any individual on the internet can attempt to exploit it. Once a victim with valid access rights views the compromised content, their browser executes the injected script. This execution context grants the malicious code full privileges associated with that user account, potentially leading to session hijacking, credential theft, unauthorized modification of geographic data, or further lateral movement within the organization's network if combined with other vulnerabilities. The persistence of the payload means a single successful injection can compromise multiple users over time without requiring repeated exploitation attempts by the attacker.
From an industry standards perspective, this vulnerability aligns closely with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. Specifically, it falls under stored XSS where malicious scripts are permanently stored on target servers. In terms of tactical mapping to MITRE ATT&CK, this behavior corresponds to techniques involving client-side code injection and potentially credential harvesting through session manipulation. The unauthenticated nature of the initial access vector highlights a critical failure in input validation controls at the application layer rather than network perimeter defenses.
Mitigation strategies must prioritize immediate patching for eligible systems. Esri has released patches for ArcGIS Server versions 12.1, 12.0, 11.5, 11.3, and 11.1 under General Availability and Extended support statuses. Organizations running these specific versions should apply the provided updates immediately to remediate the input validation flaws. For users operating on older or retired versions that are not eligible for patches, upgrading to a supported release is strongly advised as legacy software lacks modern security controls and ongoing vulnerability fixes. Additionally, implementing web application firewalls with robust XSS detection rules can provide an additional layer of defense by filtering out malicious payloads before they reach the server storage mechanisms. Regular auditing of uploaded file types and content should also be enforced to ensure that only expected data formats are processed and rendered safely within the application environment.