CVE-2025-8386 is a cross-site scripting (XSS) vulnerability classified under CWE-80, found in the AVEVA Application Server product. The flaw exists in the IDE component used for configuration-time operations, specifically allowing an authenticated user with the 'aaConfigTools' privilege to tamper with application objects' help files. By injecting malicious scripts into these help files, the attacker can create persistent XSS payloads that execute when other users access the help content. This execution can result in horizontal privilege escalation (accessing peers' privileges) or vertical privilege escalation (gaining higher privileges). The vulnerability does not impact run-time components or operations, limiting the attack surface to configuration phases. Exploitation requires the attacker to have high-level privileges and user interaction to trigger the payload, which reduces the risk of widespread automated exploitation. The CVSS v3.1 score of 6.9 reflects a medium severity, with the vector indicating local attack vector (AV:L), low attack complexity (AC:L), high privileges required (PR:H), user interaction required (UI:R), scope changed (S:C), and high confidentiality impact (C:H), low integrity (I:L), and low availability (A:L) impacts. No public exploits are currently known, and no patches have been linked yet, emphasizing the need for vigilance and proactive mitigation.

For European organizations, especially those in industrial automation, manufacturing, and critical infrastructure sectors that rely on AVEVA Application Server, this vulnerability poses a risk of unauthorized privilege escalation and potential compromise of sensitive configuration data. The ability to persistently inject XSS payloads into help files could allow attackers to execute malicious scripts in the context of other users, potentially leading to unauthorized access to configuration settings or manipulation of application behavior. Although exploitation requires authenticated access with specific privileges and user interaction, insider threats or compromised accounts could leverage this vulnerability to escalate privileges or move laterally within the environment. This could disrupt operational technology (OT) environments, cause data breaches, or degrade system integrity. The limited impact on run-time components reduces the risk to live operations but does not eliminate the threat to configuration integrity and confidentiality.

Organizations should immediately review and restrict access to the 'aaConfigTools' privilege, ensuring only trusted and necessary personnel have configuration rights. Implement strict access controls and multi-factor authentication (MFA) for users accessing the IDE component of AVEVA Application Server. Monitor and audit configuration-time operations and help file modifications for suspicious activity. Since no patches are currently available, consider isolating configuration interfaces from general network access and applying network segmentation to limit exposure. Educate users about the risks of executing untrusted scripts and enforce secure coding and input validation practices within the configuration environment. Once a patch or update is released by AVEVA, prioritize its deployment. Additionally, implement Content Security Policy (CSP) headers if possible to mitigate the impact of XSS payloads.