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CVE-2025-34291: Langflow Origin Validation Error Vulnerability

criticalknown exploitedpublic exploitCVE-2025-34291
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
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.

CSIRTS triage

vendor: Langflowproduct: LangflowCross-site request forgeryRemote code execution
What
Langflow contains an origin validation error vulnerability that allows a malicious webpage to perform cross-origin requests that include credentials.
Who is affected
Users of Langflow with an overly permissive CORS configuration.
Urgency
Immediate remediation is necessary due to the potential for full system compromise and active exploitation.
Action
Users should review and tighten CORS configurations and update Langflow.

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Details

Source
CISA Known Exploited Vulnerabilities (US · database · site)
Severity
critical
Published
2026-05-21
Exploitation
Observed in the wild (CISA KEV)

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2025-34291

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2025-34291coverage & exploitation statusNVD · CVE.org

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