CVE-2025-57520 in Decap
Summary
by MITRE • 09/10/2025
A Cross Site Scripting (XSS) vulnerability exists in Decap CMS thru 3.8.3. Input fields such as body, tags, title, and description are not properly sanitized before being rendered in the content preview pane. This enables an attacker to inject arbitrary JavaScript which executes whenever a user views the preview panel. The vulnerability affects multiple input vectors and does not require user interaction beyond viewing the affected content.
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Analysis
by VulDB Data Team • 09/13/2025
The vulnerability identified as CVE-2025-57520 represents a critical cross site scripting flaw within Decap CMS versions up to 3.8.3, classified under CWE-79 as improper neutralization of input during web output. This weakness allows attackers to inject malicious JavaScript code through various content input fields including body, tags, title, and description components. The vulnerability stems from inadequate input sanitization processes that fail to properly escape or filter user-supplied data before rendering it in the content preview pane, creating a persistent vector for malicious code execution.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious input containing JavaScript payloads within any of the affected fields. When a victim views the content preview panel, the unsanitized input executes within the browser context, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The attack requires no user interaction beyond viewing the affected content, making it particularly dangerous as it can be triggered automatically when administrators or editors preview content. This vulnerability affects the entire content management workflow since all input fields are susceptible to the same sanitization failure.
The operational impact of CVE-2025-57520 extends beyond simple script execution to compromise the integrity of the entire content management system. Attackers can leverage this vulnerability to establish persistent access to the CMS, potentially gaining administrative privileges or exfiltrating sensitive content. The lack of user interaction requirement makes this vulnerability particularly insidious as it can be exploited silently during routine content preview operations. Organizations using Decap CMS versions prior to 3.8.4 face significant risk of data breaches, as the vulnerability enables attackers to manipulate the CMS environment through the preview functionality, potentially leading to complete system compromise.
Mitigation strategies for this vulnerability should prioritize immediate patching to Decap CMS version 3.8.4 or later, which contains the necessary input sanitization fixes. Organizations should implement comprehensive input validation and output encoding measures to prevent similar issues in custom implementations. The remediation process should include thorough code reviews to ensure all user-supplied content undergoes proper sanitization before rendering, particularly in preview and edit modes. Security teams should also consider implementing content security policies and monitoring for suspicious input patterns to detect potential exploitation attempts. Additionally, regular vulnerability assessments and security training for CMS administrators can help prevent successful exploitation of similar input validation weaknesses that align with ATT&CK technique T1213 for Credential Access and T1566 for Initial Access through web-based attacks.