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CVE-2026-12945 is an authorization bypass vulnerability affecting IBM Langflow OSS versions 1.0.0 through 1.10.1. Langflow is a visual framework for building and deploying AI‑powered agents and workflows, exposing a set of HTTP API endpoints for flow execution, file management, vector store operations, and build job control. The core issue resides in two related API components: the log retrieval endpoint and the build job control endpoints.
When a user triggers a build job, Langflow generates logs that are stored and made accessible via a predictable URL pattern. The log retrieval endpoint does not perform adequate ownership checks; an authenticated user can simply modify the job ID or user identifier in the request to fetch logs belonging to any other user. Because the endpoint accepts user‑controlled keys (the job ID) without verifying that the requesting principal owns that job, it falls under CWE‑639 (Authorization Bypass Through User‑Controlled Key).
Simultaneously, the build job control endpoints – which allow starting, stopping, or cancelling builds – are exposed without requiring authentication for certain actions. In practice, an attacker who is already authenticated (with low‑privileged credentials) can combine these flaws to not only read sensitive build logs from other users but also to manipulate or cancel their in‑flight builds. The logs often contain environment variables, file paths, debugging output, and sometimes plaintext secrets or configuration data, making the information disclosure highly impactful.
The vulnerability is remotely exploitable over the network with low attack complexity and requires no user interaction. The attacker only needs valid low‑privileged credentials, which may be obtained through phishing, credential reuse, or by exploiting other weaknesses. The CVSS 3.1 vector is AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L, resulting in a base score of 7.1 (High). The confidentiality impact is rated High because log data can expose sensitive internal details, while integrity is not affected and availability is only Low (build cancellation causes disruption but not permanent damage).
IBM addressed this flaw in Langflow OSS version 1.10.2 by implementing proper ownership validation on log retrieval endpoints and enforcing authentication on all build job control endpoints. The security bulletin was published on July 14, 2026, and the NVD record was made public on July 30, 2026. Organizations running any version prior to 1.10.2 should treat this as a high‑priority remediation item, especially if Langflow is exposed to the internet or untrusted networks.
DailyCVE Form:
Platform: IBM Langflow OSS
Version: 1.0.0 – 1.10.1
Vulnerability: Improper Access Control
Severity: High (CVSS 7.1)
Date: 2026‑07‑30
Prediction: 2026‑07‑14 (v1.10.2)
What Undercode Say:
Analytics
Check if log retrieval endpoint exposes other users' logs
curl -X GET "https://langflow.example.com/api/v1/builds/{target_user_id}/logs" \
-H "Authorization: Bearer $ATTACKER_TOKEN"
Attempt to cancel another user's running build
curl -X POST "https://langflow.example.com/api/v1/builds/{target_build_id}/cancel" \
-H "Authorization: Bearer $ATTACKER_TOKEN"
Enumerate build IDs by iterating over numeric IDs
for id in {1..100}; do
curl -s -o /dev/null -w "%{http_code}" "https://langflow.example.com/api/v1/builds/$id/logs" \
-H "Authorization: Bearer $ATTACKER_TOKEN"
done
Exploit:
An authenticated attacker with a low‑privileged account sends crafted GET requests to `/api/v1/builds/{job_id}/logs` and /api/v1/builds/{job_id}/status, substituting the `job_id` parameter with identifiers belonging to other users. Because the server does not verify that the authenticated user owns the requested job, the attacker retrieves full build logs – which may include API keys, database credentials, and internal file paths – and can also issue POST requests to `/api/v1/builds/{job_id}/cancel` to terminate arbitrary builds, causing denial of service for other users’ workflows.
Protection:
Upgrade IBM Langflow OSS to version 1.10.2 or later, which enforces strict ownership checks on all build‑related endpoints and requires authentication for job control actions. If an immediate upgrade is not possible, restrict network access to the Langflow API endpoints using a firewall or reverse proxy, and enforce strong authentication policies (e.g., multi‑factor authentication) for all user accounts.
Impact:
Successful exploitation leads to unauthorized disclosure of sensitive build logs (High confidentiality impact), potentially exposing credentials, source code paths, and internal configuration data. Attackers can also cancel or disrupt other users’ builds (Low availability impact), causing workflow interruptions and potential data loss if builds are terminated mid‑execution. The integrity of the system is not directly compromised, but the exposed information may facilitate further attacks, such as privilege escalation or lateral movement within the environment.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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