CVE-2025-34330 is a vulnerability classified under CWE-434 (Unrestricted Upload of File with Dangerous Type) affecting AudioCodes Fax Server and Auto-Attendant IVR appliances up to version 2.6.23. The issue resides in the F2MAdmin web administration component, specifically in the ajaxPromptUploadFile.php script located at AudioCodes_files/utils/IVR/diagram/. This script exposes an unauthenticated file upload endpoint that accepts files and writes them directly into the C:\F2MAdmin\tmp directory. The filename is derived from application constants but lacks any authentication, authorization, or file-type validation, allowing remote attackers to upload arbitrary files. Because the upload endpoint does not require user interaction or credentials, exploitation is straightforward over the network. Attackers can overwrite prompt or music-on-hold audio files, potentially altering IVR behavior or embedding malicious payloads for subsequent attacks. Although no exploits are currently known in the wild, the vulnerability poses a risk to the integrity and availability of IVR services. The CVSS 4.0 vector (AV:N/AC:L/AT:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N) reflects network attack vector, low complexity, no authentication, no user interaction, and limited impact on confidentiality but moderate impact on integrity. The vulnerability affects a niche but critical product used in telephony environments, making it a significant concern for organizations relying on AudioCodes appliances for voice communications.

For European organizations, the impact of CVE-2025-34330 can be significant, particularly for those in telecommunications, contact centers, and enterprises using AudioCodes Fax Server and IVR appliances. Successful exploitation can lead to unauthorized modification of IVR prompts and music-on-hold files, potentially causing misinformation, disruption of customer interactions, or reputational damage. Furthermore, attackers might leverage the ability to upload arbitrary files to stage further attacks, such as deploying malware or establishing persistence within the telephony infrastructure. This could lead to service degradation or denial, impacting business continuity. Given the critical role of IVR systems in customer service and communication workflows, any compromise could disrupt operations and customer trust. Additionally, regulatory compliance risks may arise if altered IVR content leads to misinformation or breaches of communication standards. The lack of authentication and file validation increases the attack surface, making remote exploitation feasible without insider access or user interaction.

To mitigate CVE-2025-34330, organizations should implement the following specific measures: 1) Immediately restrict network access to the F2MAdmin web administration interface by isolating it within secure management VLANs or VPNs, limiting exposure to trusted administrators only. 2) Employ network-level controls such as firewalls and intrusion prevention systems to block unauthorized access to the vulnerable upload endpoint. 3) Monitor the C:\F2MAdmin\tmp directory and related IVR prompt directories for unauthorized file changes using file integrity monitoring tools. 4) Implement application-layer controls if possible, such as web application firewalls (WAFs), to detect and block suspicious file upload attempts targeting ajaxPromptUploadFile.php. 5) Coordinate with AudioCodes for timely patching or firmware updates addressing this vulnerability; apply patches as soon as they become available. 6) Conduct regular security audits and penetration testing focused on telephony infrastructure to identify and remediate similar weaknesses. 7) Educate administrators on the risks of exposing management interfaces and enforce strong access controls and logging. 8) Consider deploying endpoint protection on the appliance if supported to detect malicious files or behaviors. These targeted actions go beyond generic advice by focusing on network segmentation, monitoring, and proactive controls specific to the vulnerable component and its operational context.