Open WebUI Code Execution via Socket.IO Session Hijacking

Compliance Impact

CVE-2026-59216 allows authenticated low-privilege users to execute arbitrary code or tools in another user's authenticated session, potentially leading to unauthorized access and control over user sessions.

Such unauthorized access and potential remote code execution could lead to breaches of confidentiality, integrity, and availability of user data, which are critical concerns under regulations like GDPR and HIPAA.

If sensitive personal or health data is processed or stored within Open WebUI sessions, this vulnerability could result in non-compliance with data protection requirements, including unauthorized data access or manipulation.

Therefore, until patched, this vulnerability poses a risk to compliance with common standards and regulations that mandate strict access controls and protection of user data.

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Executive Summary

CVE-2026-59216 is a security vulnerability in Open WebUI versions prior to 0.10.0 where the system did not properly verify ownership of a session when handling Socket.IO events. Specifically, the get_event_call function delivered execute:python and execute:tool events to a client-supplied session_id after only checking that the session was connected, without confirming that the session belonged to the requesting user.

This flaw allowed authenticated users who could obtain another user's socket ID (for example, through the ydoc:document:join feature) to execute arbitrary Python code or tools within that other user's session. The vulnerability was fixed in version 0.10.0 by adding a check to ensure the target session is owned by the requesting user before allowing such event execution.

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Impact Analysis

This vulnerability can allow an authenticated low-privilege user to execute arbitrary code or tools within another user's authenticated session. If the targeted user has elevated privileges, such as an administrator, the attacker could gain access to admin-only APIs and potentially execute remote code as the server process, which may run with root privileges in the default container.

Such unauthorized code execution can lead to session hijacking, data compromise, unauthorized actions performed on behalf of the victim, and potentially full system compromise depending on the victim's privileges.

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Detection Guidance

This vulnerability involves unauthorized execution of code or tools in another user's session by exploiting improper session ownership validation in Socket.IO events.

Detection can focus on monitoring suspicious Socket.IO event activity where execute:python or execute:tool events are delivered to sessions not owned by the requesting user.

Since the system logs warnings and returns error responses when session ownership checks fail (as per the patch), reviewing application logs for such warnings can help detect exploitation attempts.

Network-level detection might involve capturing and analyzing Socket.IO traffic to identify events where session_id parameters do not match the authenticated user's session.

• Check application logs for warnings related to session ownership verification failures.
• Use network packet capture tools (e.g., tcpdump, Wireshark) to monitor Socket.IO traffic for suspicious execute:python or execute:tool events with mismatched session_ids.
• If the Open WebUI exposes APIs or debugging endpoints, use commands like `curl` or `http` to query session information and verify session ownership consistency.

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Mitigation Strategies

The primary mitigation is to upgrade Open WebUI to version 0.10.0 or later, where the vulnerability is fixed by enforcing session ownership checks before executing code or tools.

Until the upgrade can be applied, restrict access to the Open WebUI platform to trusted users only, minimizing the risk of an attacker exploiting the vulnerability.

Monitor logs for suspicious activity indicating attempts to exploit session hijacking and respond accordingly.

• Upgrade Open WebUI to version 0.10.0 or later.
• Restrict network access to the Open WebUI service to trusted users.
• Review and monitor application logs for warnings related to session ownership verification failures.

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