Description
IBM Langflow OSS 1.0.0 through 1.11.5 could allow an authenticated attacker to access another user's MCP server context due to improper cache key isolation in the MCP Tools component.
Published: 2026-09-14
Score: 4.2 Medium
EPSS: < 1% Very Low
KEV: No
Impact: Authentication Bypass
Action: Patch Now
AI Analysis

Impact

The vulnerability originates component of Langflow OSS, allowing an authenticated attacker to access or modify another user's MCP server context. This (CWE‑306) bypass of access controls can expose sensitive data stored within the MCP feature, compromising confidentiality for multiple users in a shared environment. It does not enable arbitrary code execution or privilege escalation beyond the target user's context.

Affected Systems

Affected versions include IBM Langflow OSS 1.0.0 through 1.11.5. All installations utilizing the MCP Tools module are susceptible. Critical deployments using these releases should verify their current version and assess whether they employ MCP features that store user‑specific context.

Risk and Exploitability

The CVSS score of 4.2 represents moderate severity. The EPSS score indicates a very low exploitation probability (<1%), and the vulnerability is not in the CISA KEV catalog. Exploitation requires a valid authenticated session; once logged in, an attacker can request another user's MCP context through the component, but no additional privileges are gained. The lack of public exploitation evidence keeps overall risk moderate, yet the presence of this flaw warrants timely remediation.

Generated by OpenCVE AI on September 20, 2026 at 22:19 UTC.

Remediation

Vendor Solution

IBM strongly recommends addressing the vulnerability now by upgrading Langflow OSS to version 1.11.6 https://pypi.org/project/langflow/


OpenCVE Recommended Actions

  • Upgrade IBM Langflow OSS to version 1.11.6 or later, which removes the cache key isolation flaw.
  • Enforce the lifetime of authenticated sessions.
  • Apply role‑based access controls to restrict permissions on MCP server context and minimize potential impact if isolation is compromised.

Generated by OpenCVE AI on September 20, 2026 at 22:19 UTC.

Tracking

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Advisories

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History

Tue, 15 Sep 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 14 Sep 2026 21:00:00 +0000

Type Values Removed Values Added
Description IBM Langflow OSS 1.0.0 through 1.11.5 could allow an authenticated attacker to access another user's MCP server context due to improper cache key isolation in the MCP Tools component.
Title Langflow is vulnerable to authentication bypass and insufficient session expiration
First Time appeared Ibm
Ibm langflow Oss
Weaknesses CWE-306
CPEs cpe:2.3:a:ibm:langflow_oss:1.0.0:*:*:*:*:*:*:*
cpe:2.3:a:ibm:langflow_oss:1.11.5:*:*:*:*:*:*:*
Vendors & Products Ibm
Ibm langflow Oss
References
Metrics cvssV3_1

{'score': 4.2, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N'}


Subscriptions

Ibm Langflow Oss
cve-icon MITRE

Status: PUBLISHED

Assigner: ibm

Published:

Updated: 2026-09-15T17:31:48.027Z

Reserved: 2026-06-19T22:10:15.764Z

Link: CVE-2026-12763

cve-icon Vulnrichment

Updated: 2026-09-15T17:27:01.353Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-09-14T21:17:00.440

Modified: 2026-09-16T19:24:58.293

Link: CVE-2026-12763

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-20T22:30:06Z

Weaknesses
  • CWE-306

    Missing Authentication for Critical Function