SB2026061724 - Multiple vulnerabilities in Langflow

Description

This security bulletin contains information about 2 vulnerabilities.

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

CWE-ID: CWE-400 - Resource exhaustion

CVSSv4: 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/E:P/U:Amber

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)

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

CVSSv4: 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/E:U/U:Green

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.

Remediation

Install update from vendor's website.

References

• https://github.com/langflow-ai/langflow/security/advisories/GHSA-x223-p2gf-v735
• https://github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2
• https://github.com/langflow-ai/langflow/blob/v1.9.0/src/backend/base/langflow/helpers/flow.py#L399C1-L414C67