CVE-2026-57105 in SharePoint Server
Summary
by MITRE • 08/11/2026
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network.
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Analysis
by VulDB Data Team • 08/11/2026
Cross-site scripting vulnerabilities in Microsoft Office SharePoint represent a critical security weakness that enables unauthorized attackers to inject malicious code into web pages viewed by other users. This particular flaw falls under the CWE-79 category of Cross-Site Scripting and operates by failing to properly sanitize user input during web page generation processes. The vulnerability specifically manifests when SharePoint systems do not adequately neutralize potentially dangerous input characters or sequences that could be interpreted as executable code by web browsers.
The technical implementation of this XSS vulnerability occurs within the web page generation pipeline where user-provided data is incorporated into dynamic HTML content without proper validation and sanitization measures. Attackers can exploit this weakness by crafting malicious input that, when processed and displayed by the SharePoint application, executes unintended scripts in the context of other users' browsers. This improper neutralization typically involves characters such as angle brackets, script tags, or javascript protocol handlers that are not properly escaped or filtered during content rendering.
From an operational perspective, the impact of this vulnerability extends beyond simple data theft to encompass full session hijacking capabilities and persistent malicious payload delivery. An attacker with authorized access can leverage this weakness to perform sophisticated spoofing attacks where they manipulate the SharePoint interface to appear as legitimate content while simultaneously executing malicious code. This could enable unauthorized data access, privilege escalation, or even complete system compromise depending on the attacker's level of authorization within the SharePoint environment.
The attack vector for this vulnerability typically involves an authorized user with sufficient privileges to submit content or modify web pages within the SharePoint system. Once exploited, adversaries can create persistent malicious content that affects all users who view the compromised pages or interact with the affected SharePoint components. The ATT&CK framework categorizes such techniques under T1566 - Phishing and T1059 - Command and Scripting Interpreter, emphasizing the social engineering aspects and execution methods involved in exploiting these vulnerabilities.
Organizations should implement comprehensive input validation mechanisms that sanitize all user-provided content before rendering it within SharePoint pages. This includes implementing proper HTML encoding, Content Security Policy headers, and regular security updates from Microsoft to address known XSS vulnerabilities. Additionally, privilege separation and least-privilege access controls can limit the potential damage from successful exploitation attempts, while regular security assessments should verify that input sanitization measures remain effective against evolving attack techniques.