CVE-2025-34291
Actively exploited. CVE-2025-34291 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-05-21) — exploitation has been observed in the wild, and US federal agencies are required to remediate it under BOD 22-01. Treat patching as urgent.
Public exploit code is available. Proof-of-concept or working exploit code for CVE-2025-34291 is indexed in GitHub PoC and Nuclei. Expect opportunistic scanning and exploitation attempts — prioritize remediation.
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
- 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.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Exploitation confirmedAlready exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 100% of all EPSS-scored CVEs.
Exploit availability
Public exploit or proof-of-concept code for CVE-2025-34291 is indexed in these free datasets. Available exploit code raises real-world risk independent of the CVSS score.
- GitHub PoCPublic proof-of-concept repositories on GitHub reference this CVE.look it up ↗
- NucleiA nuclei-templates detection/PoC template exists for this CVE.look it up ↗
Advisory coverage (1)
- criticalexploitedCVE-2025-34291: Langflow Origin Validation Error Vulnerabilitycisa-kev · 2026-05-21
External references
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[](https://www.csirts.com/cve/CVE-2025-34291)