CVE-2025-51857 in Halo
Summary
by MITRE • 08/05/2025
The reconcile method in the AttachmentReconciler class of the Halo system v.2.20.18LTS and before is vulnerable to XSS attacks.
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Analysis
by VulDB Data Team • 08/05/2025
The vulnerability identified as CVE-2025-51857 resides within the Halo system's AttachmentReconciler class, specifically in the reconcile method that handles attachment processing and synchronization. This flaw affects versions up to and including 2.20.18LTS, representing a critical security weakness that could enable unauthorized code execution through cross-site scripting attacks. The issue stems from insufficient input validation and output sanitization within the attachment reconciliation process, where user-supplied data is not properly escaped before being rendered in the system's web interface. The vulnerability manifests when the system processes attachments that contain malicious script payloads, which are then executed in the context of other users' browsers who view the affected content.
The technical implementation of this XSS vulnerability follows CWE-79 principles, where the system fails to properly sanitize user input during the attachment reconciliation process. When an attacker uploads or modifies an attachment with malicious content, the reconcile method processes this data without adequate filtering mechanisms. The flaw allows for both reflected and stored XSS scenarios, as the malicious scripts can be stored within the system's attachment database and executed whenever the attachment information is displayed to users. The vulnerability is particularly concerning because the AttachmentReconciler class operates at a core system level, handling critical attachment management functions that are frequently accessed by multiple users.
Operationally, this vulnerability presents significant risks to system integrity and user security across the Halo platform. An attacker could exploit this weakness to steal session cookies, perform unauthorized actions on behalf of users, or redirect victims to malicious websites. The impact extends beyond individual user compromise to potential system-wide exploitation, as the attachment reconciliation process is likely invoked during routine system operations and user interactions. The stored nature of the XSS payload means that even after the initial attack, the malicious code continues to execute against all users who view the compromised attachments, creating a persistent threat vector. This vulnerability could facilitate privilege escalation attacks if the system's attachment handling functionality is accessible to users with elevated permissions.
Mitigation strategies for CVE-2025-51857 should prioritize immediate patching of affected Halo system versions, with administrators urgently upgrading to patched releases that implement proper input validation and output sanitization. The fix should incorporate comprehensive HTML escaping for all user-supplied content within the reconcile method, utilizing established security libraries and frameworks that prevent XSS attacks. Organizations should implement Content Security Policy headers to limit script execution and establish proper input validation mechanisms that reject or sanitize potentially malicious payloads before processing. Additionally, regular security scanning of uploaded attachments and monitoring for anomalous attachment behavior should be implemented as part of the defense-in-depth strategy. The remediation process should also include user education regarding safe attachment handling practices and regular security audits of system components that process user-generated content, ensuring that similar vulnerabilities are not present in other system modules that handle external data inputs.