CVE entry · CVE-2025-34291
CVE-2025-34291: Langflow Origin Validation Error Vulnerability
Langflow contains an origin validation error vulnerability in which an overly permissive CORS configuration combined with a refresh token cookie configured as SameSite=None allows a malicious webpage to perform cross-origin requests that include credentials and successfully call the refresh endpoint. This could allow the attacker to execute arbitrary code and achieve full system compromise via obtained tokens that permit access to authenticated endpoints.
- Actively exploited: added to CISA’s KEV catalog on May 21, 2026.
- Use by ransomware: not established so far.
- Remediation deadline for US federal agencies: June 4, 2026.
Description from CISA’s KEV catalog.
What to do
- Check whether your estate includes Langflow, including internet-facing devices.
- Apply the vendor’s patch or mitigations (references below). Failing that, isolate the product or stop using it, as CISA requires of US federal agencies.
- An exploited vulnerability has often been used before it was fixed: look for signs of compromise, especially on internet-facing devices.