CVE WatchOct 8, 2026

CVE-2025-34291

Langflow Origin Validation Error Vulnerability

CVSS

8.8

High

EPSS

92.8%

p100

KEV

YES

May 21, 2026

Exploit Today

0-100

Published: Dec 5, 2025 · Last modified: Oct 8, 2026 · CWE-346

EPSS · 30d

83.6%EPSS · 30 days92.8%

2026-09-162026-10-14

KEV catalog record

Product

Langflow / Langflow

Vulnerability

Langflow Origin Validation Error Vulnerability

Added to KEV

May 21, 2026

Remediate by

Jun 4, 2026

Known ransomware use

Summary 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.

Required action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Notes

This vulnerability could affect an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: https://github.com/langflow-ai/langflow ; https://github.com/langflow-ai/langflow/releases/tag/v1.9.3; https://github.com/langflow-ai/langflow/issues/11465#event-25774545848 ; https://nvd.nist.gov/vuln/detail/CVE-2025-34291

Technical description

Langflow versions up to and including 1.6.9 contain a chained vulnerability that enables account takeover and remote code execution. An overly permissive CORS configuration (allow_origins='*' with allow_credentials=True) 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. An attacker-controlled origin can therefore obtain fresh access_token / refresh_token pairs for a victim session. Obtained tokens permit access to authenticated endpoints — including built-in code-execution functionality — allowing the attacker to execute arbitrary code and achieve full system compromise.

Official references

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