CVE-2026-55255: Langflow Authorization Bypass Through User-Controlled Key Vulnerability

Summary

Langflow contains an authorization bypass through user-controlled key vulnerability which allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request.

Remediation

Inventory every Langflow Langflow deployment, including staging.
No fixed version appears in the public sources yet. Check the references below and the vendor directly.
Review logs from before the change for signs of exploitation.

CISA required actionApply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

References

Advisoryhttps://github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2
Advisoryhttps://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
Advisoryhttps://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
Advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2026-55255
Advisoryhttps://webflow.sysdig.com/blog/understanding-langflow-cve-2026-55255-and-why-higher-cvss-vulnerabilities-arent-always-the-most-exploited
Referencehttps://github.com/langflow-ai/langflow/pull/12832
Referencehttps://github.com/langflow-ai/langflow/commit/2c9f498d664a3c32698b57d7c5e752625291060e
Referencehttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-55255