CVE-2026-55255

Langflow: IDOR Vulnerability in `/api/v1/responses` Endpoint Allows Authenticated Attackers to Access Another User's Flow

CVSS 3.1 High 8.4Known exploited (CISA KEV)

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L

Description

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.

Key data

CVSS 3.1 High 8.4

Score published by GitHub_M in the CVE record.

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L

Attack vector: Network
The vulnerable component can be reached over a network, possibly from the Internet.
Attack complexity: High
The attack depends on conditions outside the attacker's control, so it takes preparation.
Privileges required: Low
A basic user account is needed.
User interaction: None
No action from any user is needed.
Scope: Changed
The impact can reach other components beyond the vulnerable one.
Confidentiality impact: High
Serious or total effect on the secrecy of data.
Integrity impact: High
Serious or total effect on the trustworthiness of data.
Availability impact: Low
Limited effect on availability.

Metric	Value	What it means
Attack vector	Network	The vulnerable component can be reached over a network, possibly from the Internet.
Attack complexity	High	The attack depends on conditions outside the attacker's control, so it takes preparation.
Privileges required	Low	A basic user account is needed.
User interaction	None	No action from any user is needed.
Scope	Changed	The impact can reach other components beyond the vulnerable one.
Confidentiality impact	High	Serious or total effect on the secrecy of data.
Integrity impact	High	Serious or total effect on the trustworthiness of data.
Availability impact	Low	Limited effect on availability.

CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at first.org/cvss.

EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.

Score: 0.00887 (0.9% probability)
Percentile: 59.6%
Scores of: Nov 10, 2026
Model: v2026.06.15

CISA Known Exploited Vulnerabilities

This CVE is listed in the CISA KEV catalog.

Name in the catalog: Langflow Authorization Bypass Through User-Controlled Key Vulnerability
Added to the catalog: Jul 7, 2026
Federal due date: Jul 10, 2026

CISA assessment as of Jul 8, 2026

Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA.

Exploitation: Recorded by CISA as active
Automatable: no
Technical impact: total

Weakness (CWE)

CWE catalog version 5.0.

CWE-639Authorization Bypass Through User-Controlled Key

Affected products

Products listed in the CVE record, as the CNA published them.

langflow-ai langflow
- affected: < 1.9.1

References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

Timeline

ID reservedJun 16, 2026
Record publishedJun 23, 2026
Added to CISA KEVJul 7, 2026
Record last updatedOct 7, 2026

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Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 19:09 UTC. Sources and licenses