CVE-2025-47151: Entrouvert Lasso RCE Vulnerability

CVE-2025-47151 Overview

CVE-2025-47151 is a type confusion vulnerability in the lasso_node_impl_init_from_xml functionality of Entr'ouvert Lasso, a free software library implementing Liberty Alliance and SAML 2.0 protocols. The vulnerability exists in versions 2.5.1 and 2.8.2 of the library. A specially crafted SAML response can lead to arbitrary code execution, allowing an attacker to send a malformed SAML response to trigger this vulnerability.

Critical Impact

This type confusion vulnerability enables remote attackers to achieve arbitrary code execution without authentication by sending a malicious SAML response to applications using the vulnerable Lasso library.

Affected Products

• Entr'ouvert Lasso version 2.5.1
• Entr'ouvert Lasso version 2.8.2
• Applications and services implementing SAML authentication using vulnerable Lasso versions

Discovery Timeline

• 2025-11-05 - CVE-2025-47151 published to NVD
• 2025-11-07 - Last updated in NVD database

Technical Details for CVE-2025-47151

Vulnerability Analysis

This vulnerability is classified as CWE-843 (Access of Resource Using Incompatible Type, commonly known as Type Confusion). The flaw resides in the lasso_node_impl_init_from_xml function, which is responsible for parsing and initializing nodes from XML data during SAML response processing.

Type confusion vulnerabilities occur when a program accesses a resource using a type that is incompatible with its actual type. In this case, when the Lasso library processes a SAML response, the XML parsing logic can be tricked into treating data of one type as another type, leading to memory corruption and ultimately arbitrary code execution.

The vulnerability is particularly dangerous because SAML (Security Assertion Markup Language) is widely used for single sign-on (SSO) authentication in enterprise environments. Any application or identity provider using the affected Lasso library versions could be vulnerable to this attack.

Root Cause

The root cause is improper type handling in the XML node initialization code within the lasso_node_impl_init_from_xml function. When processing XML elements from SAML responses, the library fails to properly validate that the type of a parsed node matches the expected type before using it. This allows an attacker to craft XML structures that cause the library to interpret memory regions as different data types than they actually are.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by:

1. Identifying an application or service using a vulnerable version of the Lasso library for SAML authentication
2. Crafting a malicious SAML response containing specially structured XML elements designed to trigger the type confusion
3. Sending the malformed SAML response to the target application's SAML endpoint
4. The vulnerable lasso_node_impl_init_from_xml function processes the malicious XML, triggering the type confusion
5. Upon successful exploitation, the attacker achieves arbitrary code execution on the target system

The vulnerability is documented in the Talos Intelligence Vulnerability Report (TALOS-2025-2193) which provides additional technical details about the exploitation mechanics.

Detection Methods for CVE-2025-47151

Indicators of Compromise

• Unexpected crashes or abnormal behavior in applications using Lasso for SAML authentication
• Anomalous SAML response payloads with unusual XML structures targeting XML parsing functions
• Evidence of code execution following SAML authentication attempts
• Memory corruption indicators in Lasso library processes

Detection Strategies

• Deploy network intrusion detection rules to identify malformed SAML responses with suspicious XML structures
• Monitor application logs for SAML parsing errors or unexpected exceptions in the Lasso library
• Implement deep packet inspection on SAML endpoints to detect potentially malicious payloads
• Use application performance monitoring to detect unusual behavior during SAML processing

Monitoring Recommendations

• Enable verbose logging on SAML authentication endpoints to capture detailed request/response data
• Configure alerting for unusual SAML traffic patterns or error rates
• Monitor system resources on servers running applications with Lasso dependencies for signs of exploitation
• Implement file integrity monitoring on systems using vulnerable Lasso versions

How to Mitigate CVE-2025-47151

Immediate Actions Required

• Inventory all applications and services using the Entr'ouvert Lasso library to identify vulnerable deployments
• Upgrade Lasso library to a patched version that addresses CVE-2025-47151
• If immediate patching is not possible, consider temporarily disabling SAML authentication or implementing additional network controls
• Review logs for any evidence of exploitation attempts against vulnerable systems

Patch Information

Organizations should check with Entr'ouvert for official security patches addressing this vulnerability. The Talos Intelligence advisory provides additional details on remediation. Ensure that all instances of Lasso versions 2.5.1 and 2.8.2 are identified and upgraded to a secure version.

Workarounds

• Implement Web Application Firewall (WAF) rules to inspect and filter malicious SAML responses before they reach vulnerable applications
• Restrict network access to SAML endpoints to trusted identity providers only using firewall rules or network segmentation
• Consider using an alternative SAML library until a patch is applied if feasible
• Enable additional input validation on SAML responses at the application layer where possible