CVE-2025-34291

Langflow · Langflow · Langflow Origin Validation Error Vulnerability

What an attacker can reach

CVSS 9.4 CRITICAL. The score is a summary; these three components are the part that decides whether something scanning the internet can use it.

This describes the vulnerability. It says nothing about whether your systems run it.

How likely

EPSS puts the probability of exploitation in the next 30 days at 0.9281, which places it in the top 1% of all tracked CVEs. The percentile is the more useful half: 0.18 in absolute terms sounds low until you know most of the internet-facing software in the world scores under that.

Time

What CISA says to do

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

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.

Sources

• CISA Known Exploited Vulnerabilities catalog — exploited status, dates, required action
• NVD — CVSS vector, weakness, references
• github.com/langflow-ai/langflow
• www.obsidiansecurity.com/blog/cve-2025-34291-critical-account-takeover-a
• www.vulncheck.com/advisories/langflow-cors-misconfiguration-to-token-hij
• www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-
• FIRST EPSS record — probability and percentile