CVE-2025-20236: Cisco Webex Teams RCE Vulnerability

CVE-2025-20236 Overview

A vulnerability exists in the custom URL parser of Cisco Webex App that could allow an unauthenticated, remote attacker to persuade a user to download arbitrary files, which could subsequently allow the attacker to execute arbitrary commands on the host of the targeted user. This vulnerability stems from insufficient input validation when Cisco Webex App processes meeting invite links, making it a significant threat to enterprise collaboration environments.

Critical Impact

Successful exploitation allows an attacker to execute arbitrary commands with the privileges of the targeted user, potentially leading to complete system compromise, data exfiltration, or lateral movement within corporate networks.

Affected Products

• Cisco Webex Teams version 44.6
• Cisco Webex Teams versions 44.6.0.29928 and 44.6.0.30148
• Cisco Webex Teams versions 44.7, 44.7.0.30141, and 44.7.0.30285

Discovery Timeline

• April 16, 2025 - CVE-2025-20236 published to NVD
• August 1, 2025 - Last updated in NVD database

Technical Details for CVE-2025-20236

Vulnerability Analysis

This vulnerability is classified under CWE-829 (Inclusion of Functionality from Untrusted Control Sphere), indicating that the Cisco Webex App incorporates or relies on functionality from external sources without proper validation. The attack requires user interaction—specifically, the victim must click on a crafted meeting invite link—but no prior authentication or privileges are required by the attacker to initiate the attack.

The vulnerability affects the custom URL parser component of the Cisco Webex App, which is responsible for handling meeting invitation links. When processing specially crafted URLs, the application fails to adequately validate the input, allowing attackers to manipulate the URL structure to trigger arbitrary file downloads and subsequent command execution.

Root Cause

The root cause of CVE-2025-20236 lies in insufficient input validation within the custom URL parser of Cisco Webex App. When the application processes meeting invite links, it does not properly sanitize or validate URL parameters and paths. This allows an attacker to craft malicious URLs that bypass security controls and direct the application to download arbitrary files from attacker-controlled servers. Once downloaded, these files can be executed with the privileges of the user running the Webex application.

Attack Vector

The attack vector for this vulnerability is network-based and requires minimal complexity to execute. An attacker exploits this vulnerability through the following sequence:

1. The attacker crafts a malicious meeting invite link containing manipulated URL parameters
2. The attacker distributes this link via email, messaging platforms, or other communication channels
3. When a victim clicks the crafted link, the Webex App's URL parser processes it without adequate validation
4. The application is tricked into downloading arbitrary files from attacker-controlled sources
5. The downloaded malicious payload executes with the privileges of the targeted user

The vulnerability is particularly dangerous in enterprise environments where Webex is widely deployed for collaboration, as meeting invite links are routinely shared and trusted by users.

Detection Methods for CVE-2025-20236

Indicators of Compromise

• Unexpected file downloads initiated by the Webex application, particularly executables or scripts from non-Cisco domains
• Unusual child processes spawned by the Webex App process (CiscoCollabHost.exe, webexapp.exe)
• Network connections from Webex processes to unknown or suspicious external domains
• Modified or newly created files in user-writable directories following Webex link interactions

Detection Strategies

• Monitor for anomalous URL patterns in Webex-related network traffic, particularly those with unusual path structures or query parameters
• Implement application-level logging to capture URL processing events in Webex installations
• Deploy endpoint detection rules to identify when Webex processes attempt to download and execute files from untrusted sources
• Utilize SentinelOne's behavioral AI to detect post-exploitation activities such as unauthorized command execution

Monitoring Recommendations

• Enable enhanced logging for the Cisco Webex App to capture URL processing events and file download activities
• Monitor process creation events where the parent process is a Webex application component
• Implement network segmentation and monitoring to detect unusual outbound connections from collaboration tools
• Configure security alerts for any file executions originating from temporary directories associated with Webex operations

How to Mitigate CVE-2025-20236

Immediate Actions Required

• Update Cisco Webex App to the latest patched version as specified in the Cisco Security Advisory
• Educate users about the risks of clicking on meeting links from untrusted or unexpected sources
• Implement email gateway filtering to scrutinize Webex meeting invite links before delivery to end users
• Review and restrict application permissions to limit the impact of potential exploitation

Patch Information

Cisco has released security updates to address this vulnerability. Organizations should consult the official Cisco Security Advisory for detailed patch information and upgrade paths. Affected versions include Cisco Webex Teams 44.6 through 44.7.0.30285. Administrators should prioritize patching due to the remote code execution potential of this vulnerability.

Workarounds

• Implement strict URL filtering at the network perimeter to block suspicious Webex meeting links until patches can be applied
• Configure endpoint protection policies to block execution of downloaded files from untrusted sources
• Utilize application control policies to restrict which processes the Webex App can spawn
• Deploy web proxy rules to inspect and validate Webex-related URLs before allowing user access

# Example: Block suspicious Webex URL patterns at the proxy level
# Add to proxy blocklist configuration
# Block meeting links with suspicious path components
*.webex.*/*/../*
*.webex.*/download/*
# Monitor and log all Webex meeting link access for security review