SB2026061724 - Multiple vulnerabilities in Langflow

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Main Vulnerability Database SB2026061724

SB2026061724 - Multiple vulnerabilities in Langflow

Published: June 17, 2026 Updated: October 16, 2026

Security Bulletin ID SB2026061724
CSH Severity
High
Patch available
YES
Number of vulnerabilities 4
Exploitation vector Remote access
Highest impact Privilege escalation

Breakdown by Severity

High 50% Medium 25% Low 25%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 4 vulnerabilities.


1) Resource exhaustion (CVE-ID: CVE-2026-55450)

CWE-ID: CWE-400 - Resource exhaustion

CVSSv4: 8.8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to application does not properly control consumption of internal resources. A remote attacker can upload any amount of data to the server without any limitations and perform a denial of service (DoS) attack or gain access to sensitive information.


2) Authorization bypass through user-controlled key (CVE-ID: CVE-2026-55255) Exploited

CWE-ID: CWE-639 - Authorization Bypass Through User-Controlled Key

CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N]


The vulnerability allows a remote user to execute another user's flow and disclose sensitive information.

The vulnerability exists due to improper access control in the /api/v1/responses endpoint and get_flow_by_id_or_endpoint_name helper function when handling requests that reference a flow by UUID. A remote user can send a specially crafted request with a victim's flow ID to execute another user's flow and disclose sensitive information.

The issue occurs only for UUID-based flow lookups; endpoint_name-based lookups apply a user ownership check.


3) Missing Authentication for Critical Function (CVE-ID: N/A)

CWE-ID: CWE-306 - Missing Authentication for Critical Function

CVSSv4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to execute arbitrary code or cause a denial of service.

The vulnerability exists due to missing authentication for a critical function in the webhook authentication logic in AuthService.get_webhook_user when handling webhook requests with webhook authentication disabled. A remote attacker can send a specially crafted POST request to trigger execution of a flow to execute arbitrary code or cause a denial of service.

Exploitation requires knowledge of a valid flow UUID and affects deployments where the webhook authentication setting is disabled.


4) Authorization bypass through user-controlled key (CVE-ID: CVE-2026-105699)

CWE-ID: CWE-639 - Authorization Bypass Through User-Controlled Key

CVSSv4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote user to read other users' flow-backed files and disclose sensitive information across project boundaries.

The vulnerability exists due to missing ownership and project-membership checks in Langflow's MCP handle_read_resource() function when processing resource URIs supplied through resources/read. A remote user can connect to a project-scoped MCP endpoint they own and submit a file-download URI containing another user's flow ID and filename to retrieve the corresponding file without authorization.


Remediation

Install update from vendor's website.

References