CVE-2026-55255
Langflow Authorization Bypass Through User-Controlled Key Vulnerability
Langflow Langflow
Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.1, an Insecure Direct Object Reference (IDOR) vulnerability in /api/v1/responses endpoint allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request. This vulnerability is fixed in 1.9.1.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 7 July 2026. US federal agencies were required to remediate it by 10 July 2026.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 29.1%, which is higher than 98% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
Frequently asked questions
Is CVE-2026-55255 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2026-55255.
What does CVE-2026-55255 affect?
CVE-2026-55255 affects Langflow Langflow. Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.1, an Insecure Direct Object Reference (IDOR) vulnerability in /api/v1/responses endpoint allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request. This vulnerability is fixed in 1.9.1.
How severe is CVE-2026-55255?
CVE-2026-55255 is rated HIGH with a CVSS base score of 8.4. EPSS puts the probability of exploitation in the next 30 days at 29.1%, higher than 98% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 10 July 2026.
How should organisations respond to CVE-2026-55255?
Apply the vendor patch for Langflow Langflow as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.