CVE-2026-101158: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in Arista Networks CloudVision Portal

This vulnerability (CVE-2026-101158) is an improper input neutralization issue (CWE-79) in the Fileserver upload API of Arista Networks CloudVision Portal. It allows an authenticated attacker with file upload privileges to store malicious scripts that execute in the context of other users' browsers. Successful exploitation can hijack web sessions and grant full access to victim accounts, including administrative permissions. The vulnerability affects multiple versions spanning from 1.0.0 through 2026.2.0 with some version ranges specified. The CVSS 3.1 score of 8.4 reflects the network attack vector, low attack complexity, high privileges required, user interaction needed, scope change, and high impact on confidentiality, integrity, and availability. No vendor advisory or patch information is available to confirm remediation status.

An authenticated attacker with file upload privileges can execute stored cross-site scripting attacks, potentially hijacking other users' web sessions. This can lead to full compromise of victim accounts, including administrative access, which may result in unauthorized control over the CloudVision Portal environment.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict file upload privileges to trusted users only and monitor for suspicious activity related to file uploads and user sessions.