Security Bulletin
Summary
A session ID namespace bypass vulnerability existed in Langflow OSS' POST /api/v1/build_public_tmp/{flow_id}/flow endpoint that allowed unauthenticated attackers to access chat history from other users' sessions. The endpoint accepted an inputs.session parameter that could override the session ID used during flow execution. When a PUBLIC flow contained a Memory (Message History) component with an empty session_id field, the component used the caller-supplied session ID without proper isolation. Because the public build_public_tmp path did not enforce session namespacing, unauthenticated callers could provide arbitrary session IDs and retrieve stored chat history. This was exploitable against sessions created through the authenticated POST /api/v1/run/{flow_id} path, where the default session_id equals the flow UUID (visible in URLs), making target sessions predictable.
Vulnerability Details
CVEID: CVE-2026-7787
DESCRIPTION: Langflow OSS could allow an authenticated user to read or modify sensitive information by bypassing authentication using insecure direct object references.
CWE: CWE-639: Authorization Bypass Through User-Controlled Key
CVSS Source: IBM
CVSS Base score: 7.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
Affected Products and Versions
| Affected Product(s) | Version(s) |
| Langflow OSS | 1.0.0-1.9.1 |
Remediation/Fixes
IBM strongly recommends addressing the vulnerability now by upgrading Langflow OSS to version 1.9.2.
Workarounds and Mitigations
None
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References
Acknowledgement
Change History
08 Jun 2026: Initial Publication
*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.
Disclaimer
According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES ""AS IS"" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions.
Document Location
Worldwide
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Document Information
Modified date:
08 June 2026
Initial Publish date:
08 June 2026
UID
ibm17275453