CISA Warns of Critical Langflow Origin Validation Flaw (CVE-2024-28219)

Key Takeaways

• A critical vulnerability, CVE-2025-34291, has been identified in Langflow, an AI workflow tool.
• The flaw, an origin validation error due to an overly permissive Cross-Origin Resource Sharing (CORS) configuration, is actively being exploited.
• Attackers can leverage this vulnerability to gain unauthorized access, steal refresh tokens, and potentially achieve full system compromise.
• CISA has added this CVE to its Known Exploited Vulnerabilities (KEV) Catalog, mandating urgent remediation for federal agencies and strongly advising it for all organizations.

CISA Flags Critical Langflow Vulnerability Under Active Exploitation

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has issued an urgent alert regarding CVE-2025-34291, a severe vulnerability in Langflow, by adding it to its Known Exploited Vulnerabilities (KEV) Catalog. This action confirms that the flaw is under active exploitation, necessitating immediate attention and remediation across affected systems.

Langflow, a widely used platform for developing and deploying AI-driven workflows, is at the heart of this critical security concern. The vulnerability stems from an origin validation error, specifically an overly permissive Cross-Origin Resource Sharing (CORS) configuration within the application.

When this misconfiguration is combined with a refresh token cookie set to SameSite=None, it creates a dangerous pathway. Malicious websites can then execute authenticated cross-origin requests, bypassing security measures and potentially compromising the system.

Understanding the Attack Vector

This critical weakness allows threat actors to perform several malicious actions, including sending unauthorized requests from a victim’s browser, accessing sensitive refresh tokens, invoking backend authentication endpoints, and potentially executing arbitrary code to achieve a full system compromise.

Categorized under CWE-346 (Origin Validation Error), the flaw highlights a fundamental issue in how Langflow validates the origin of incoming requests. In a typical attack scenario, an attacker would lure a user to a specially crafted malicious webpage. Due to the flawed CORS policy and the specific cookie configuration, the victim’s browser automatically includes their authentication credentials in cross-origin requests to the Langflow instance.

This enables the attacker to interact silently with Langflow’s API, particularly its refresh endpoint, without the user’s knowledge. Once refresh tokens are acquired, attackers can generate new access tokens, establish persistent access, interact with authenticated endpoints, and escalate their privileges within the compromised system.

Such attacks pose a significant risk, especially in environments where Langflow is integrated with critical AI pipelines, various APIs, or cloud-based services, where a breach could have far-reaching consequences.

Mandatory Remediation and Broader Implications

CISA officially added CVE-2025-34291 to its KEV catalog on May 21, 2026, signaling the serious threat this vulnerability poses to both federal and enterprise IT infrastructures. Federal Civilian Executive Branch (FCEB) agencies are now mandated to remediate this vulnerability by the specified due date under Binding Operational Directive (BOD) 22-01.

The inclusion of this flaw in the KEV catalog underscores a growing trend where misconfigured web security controls in modern applications are becoming prime targets for attackers. As AI platforms like Langflow gain wider adoption, attackers are increasingly focusing on weaknesses in authentication flows and API security.

What You Should Do

• Apply Updates Immediately: Prioritize and apply all vendor-provided patches or updates for Langflow without delay.
• Review CORS Configurations: Thoroughly review and restrict Cross-Origin Resource Sharing (CORS) configurations to only explicitly trusted origins.
• Cookie Security: Avoid using SameSite=None for sensitive authentication cookies unless absolutely necessary and ensure proper secure flags are set.
• Implement Additional Protections: Deploy supplementary security measures such as Cross-Site Request Forgery (CSRF) tokens and strict origin validation mechanisms.
• Monitor for Suspicious Activity: Enhance monitoring of logs for any unusual cross-origin requests or instances of token abuse.
• Consider Discontinuation: If immediate mitigations are not available or feasible, consider discontinuing the use of Langflow in production environments until a secure solution can be implemented.

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