Fax ServerApplication · Audiocodes

CVE-2025-34329

CRITICAL · 9.8 CVSS v3.1 Published 2025-11-19
Fix available
A fix is available. Upgrade to after 2.6.23 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
AudioCodes Fax Server and Auto-Attendant IVR appliances versions up to and including 2.6.23 expose an unauthenticated backup upload endpoint at AudioCodes_files/ajaxBackupUploadFile.php in the F2MAdmin web interface. The script derives a backup folder path from application configuration, creates the directory if it does not exist, and then moves an uploaded file to that location using the attacker-controlled filename, without any authentication, authorization, or file-type validation. On default Windows deployments where the backup directory resolves to the system drive, a remote attacker can upload web server or interpreter configuration files that cause a log file or other server-controlled resource to be treated as executable code. This allows subsequent HTTP requests to trigger arbitrary command execution under the web server account, which runs as NT AUTHORITY\\SYSTEM.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

AudioCodes Fax Server and Auto-Attendant IVR appliances up to version 2.6.23 have an unauthenticated arbitrary file upload vulnerability in the F2MAdmin web interface (ajaxBackupUploadFile.php). The script accepts uploads without authentication, authorization, or file-type validation, and uses the attacker-controlled filename to store files in a configurable backup directory. On default Windows deployments where this directory resolves to the system drive, attackers can upload web shell or configuration files that get executed, achieving remote code execution as NT AUTHORITY\SYSTEM.

MitigationApply vendor patch (version 2.6.24 or later). If unavailable, disable the F2MAdmin web interface, restrict network access to the management interface, and implement WAF rules to block unauthorized upload requests.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Fax ServerApplication
Affected:<= 2.6.23
Interactive Voice ResponseApplication
Affected:<= 2.6.23

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify AudioCodes Fax Server or IVR installation
    Locate the AudioCodes application installation directory on the system (typically under Program Files or the system drive). Check for Fax Server or IVR application files.
    Affected if AudioCodes Fax Server or IVR software is installed on the system
  2. Verify installed software version
    Locate the version information for the installed AudioCodes software. This is typically found in the application GUI, an about page, or in installed configuration files.
    Affected if The installed version is 2.6.23 or earlier
  3. Confirm F2MAdmin web interface is enabled
    Check if the F2MAdmin web interface is accessible on the appliance. This is typically accessible via HTTP/HTTPS on the management port (commonly port 80/443 or a custom management port).
    Affected if The F2MAdmin web interface is exposed and reachable on the network
  4. Verify ajaxBackupUploadFile.php is present
    Attempt to access the path /F2MAdmin/ajaxBackupUploadFile.php (or the equivalent path on the specific deployment) via HTTP/HTTPS to confirm the script exists.
    Affected if The ajaxBackupUploadFile.php script is accessible and responds to requests
  5. Check backup directory configuration
    Examine the web server or application configuration to determine the configured backup directory path where uploaded files are stored.
    Affected if The backup directory resolves to the system drive or a web-accessible location where uploaded files can be executed

The environment is affected if AudioCodes Fax Server or IVR version 2.6.23 or earlier is installed with the F2MAdmin web interface accessible and the ajaxBackupUploadFile.php script present.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to a release after 2.6.23
Interim mitigation

Apply vendor patch (version 2.6.24 or later). If unavailable, disable the F2MAdmin web interface, restrict network access to the management interface, and implement WAF rules to block unauthorized upload requests.

Fix this in Fax Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA2.0 h
8.0 hours of engineering $1,390
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,224.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-34329 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-34329 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data