CVE-2026-20062: Cisco ASA Privilege Escalation Flaw

CVE-2026-20062 Overview

A vulnerability exists in the Command Line Interface (CLI) of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software when operating in multiple context mode. This security flaw could allow an authenticated, local attacker with administrative privileges in one context to copy files to or from another context, including sensitive configuration files.

The vulnerability stems from improper access controls for Secure Copy Protocol (SCP) operations when the CiscoSSH stack is enabled. An attacker could exploit this vulnerability by authenticating to a non-admin context of the device and issuing crafted SCP copy commands to read, create, or overwrite files belonging to another context, including the admin and system contexts.

Critical Impact

Authenticated attackers can bypass context isolation boundaries to access, modify, or overwrite sensitive configuration files across multiple security contexts, potentially compromising the entire multi-tenant firewall deployment.

Affected Products

• Cisco Secure Firewall Adaptive Security Appliance (ASA) Software in multiple context mode
• Cisco ASA deployments with CiscoSSH stack enabled
• Multi-context ASA configurations with SCP functionality

Discovery Timeline

• March 4, 2026 - CVE-2026-20062 published to NVD
• March 5, 2026 - Last updated in NVD database

Technical Details for CVE-2026-20062

Vulnerability Analysis

This vulnerability is classified under CWE-279 (Incorrect Execution-Assigned Permissions), indicating a fundamental flaw in how the ASA Software enforces access controls between security contexts. In Cisco ASA multiple context mode, the firewall is partitioned into multiple virtual devices (contexts), each operating as an independent firewall with its own security policies, interfaces, and administrators.

The security boundary between contexts is critical in multi-tenant deployments where different organizations or business units share the same physical appliance. This vulnerability undermines that isolation by allowing an administrator of one context to access files belonging to other contexts, including the privileged admin and system contexts.

The local attack vector requires the attacker to have valid administrative credentials for a non-admin context. While the attacker cannot directly enumerate or list files from another context and must know the exact file path, successful exploitation could lead to exposure of sensitive configuration data, credential theft, or configuration tampering.

Root Cause

The root cause of this vulnerability is improper access control implementation in the SCP operations when the CiscoSSH stack is enabled. Specifically, the ASA Software fails to properly validate and enforce context boundaries when processing SCP copy commands, allowing file operations to traverse context isolation boundaries.

The CiscoSSH stack, when enabled, does not adequately verify that the source and destination paths of SCP operations remain within the authorized context of the authenticated administrator. This allows crafted SCP commands to reference file paths belonging to other contexts.

Attack Vector

The attack requires local access to the device through the CLI with valid administrative credentials for a non-admin context. The attacker must:

1. Authenticate to a non-admin context with valid administrative credentials
2. Have the CiscoSSH stack enabled on the target ASA device
3. Know the exact file path of the target file in another context
4. Issue crafted SCP copy commands to read from or write to files in unauthorized contexts

The exploitation mechanism involves crafting SCP commands that specify file paths outside the attacker's authorized context. While the attacker cannot list directory contents of other contexts, knowledge of standard ASA configuration file locations (such as startup-config or running-config) could enable targeted attacks against sensitive files.

Successful exploitation allows the attacker to read sensitive configuration files (potentially containing credentials, security policies, or network architecture details), create new files in other contexts, or overwrite existing files to modify configurations. However, the attacker cannot directly impact the availability of services in other contexts through this vulnerability.

Detection Methods for CVE-2026-20062

Indicators of Compromise

• Unusual SCP operations in ASA audit logs that reference file paths outside the initiating context
• Administrative login activity to non-admin contexts followed by SCP commands targeting system or admin context paths
• Unexpected modifications to configuration files in the admin or system contexts
• Cross-context file access attempts logged in ASA security event logs

Detection Strategies

• Enable comprehensive logging of all SCP operations on ASA devices operating in multiple context mode
• Monitor for SCP commands containing path references that appear to target other contexts (e.g., references to disk0:/admin/ or system/ from non-admin context sessions)
• Implement SIEM correlation rules to detect administrative actions followed by cross-context file operations
• Review ASA audit logs for unusual file copy patterns or access to sensitive configuration files

Monitoring Recommendations

• Enable and review AAA accounting logs for all administrative sessions across all contexts
• Configure syslog forwarding to a centralized SIEM for real-time analysis of ASA events
• Implement file integrity monitoring for critical configuration files in admin and system contexts
• Establish baseline patterns for legitimate SCP usage to identify anomalous activity

How to Mitigate CVE-2026-20062

Immediate Actions Required

• Review the Cisco Security Advisory for specific remediation guidance
• Audit all administrative accounts across all contexts and ensure principle of least privilege
• Consider temporarily disabling the CiscoSSH stack if not operationally required until patches are applied
• Review and restrict which administrators have access to non-admin contexts

Patch Information

Cisco has released security updates to address this vulnerability. Administrators should consult the Cisco Security Advisory for specific software versions containing the fix and upgrade guidance for their deployment.

Organizations should prioritize patching based on their exposure level, particularly those running multi-tenant ASA deployments where context isolation is critical to security boundaries between different organizations or business units.

Workarounds

• Disable the CiscoSSH stack if SCP functionality is not required for operations
• Implement strict administrative access controls limiting which users can authenticate to non-admin contexts
• Use out-of-band management networks to reduce local access attack surface
• Monitor and alert on all SCP operations performed from non-admin contexts

Consult the Cisco Security Advisory for additional mitigation options and configuration recommendations specific to your deployment:

# Example: Review CiscoSSH stack configuration status
show running-config ssh

# Example: Review context administrative access
show running-config | include context
show context detail

# Consult Cisco documentation for disabling CiscoSSH stack if not required