CVE-2025-34291 Langflow Langflow: software flaw
In plain words: A mistake in the software that attackers have found a way to abuse. Depends on the product — see the description and the vendor advisory.
Confirmed exploited by CISA on · US federal patch deadline Jun 4, 2026
What to do
- Install Langflow's security update for Langflow. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Keep a list of every internet-facing server you run so nothing is forgotten.
- Patch anything in this catalog first, ahead of normal patch cycles.
- Put admin and file-transfer apps behind a VPN or single sign-on instead of the open internet.
Who is affected
Work IT. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.
What's at risk: Mass data theft and ransomware: a single flaw in a file-transfer or email server has exposed thousands of organisations at once.
The details
- Official name
- Langflow Origin Validation Error Vulnerability
- Product
- Langflow Langflow
- CISA description
- 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.
- Type of flaw
- Software flaw (CWE-346)
- Confirmed exploited
- May 21, 2026
- US federal patch deadline
- Jun 4, 2026
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Answering about CVE-2025-34291 ·
Questions about CVE-2025-34291
Is CVE-2025-34291 being exploited?
Yes. CISA added CVE-2025-34291 to its Known Exploited Vulnerabilities catalog on May 21, 2026, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2025-34291?
Install Langflow's security update for Langflow. If no update exists, follow the vendor's workaround or stop using the product until one ships. Keep a list of every internet-facing server you run so nothing is forgotten.
Am I affected by CVE-2025-34291?
Only if you use Langflow Langflow. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.