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Open WebUI suffers from a critical missing authorization vulnerability tracked as CVE-2026-59714.
The flaw originates within the chat completion API pipeline and the socket message emitter mechanism.
Specifically, when handling incoming requests to the chat endpoints, user-supplied message identifiers are accepted directly.
These identifiers are passed down to the internal channel emitter without verifying whether the user owns the target channel.
While standard REST channel routes properly enforce access controls and return 403 errors, the chat completion pipeline fails closed.
An authenticated user can supply a crafted chat ID string targeting private channels or direct message channels they have no access to.
The system executes an unchecked database write operation using this unvalidated message ID parameter.
Consequently, model outputs or provider error strings are written directly into the victim’s channel message history.
This cross-channel message overwrite condition allows attackers to inject arbitrary text or corrupt conversation data.
The vulnerability bypasses previous partial patches that only validated initial model identifiers in multimodel mappings.
Because the emitter function executes updates without re-checking channel ID association, integrity is completely lost.
Exploitation requires valid user authentication, but zero privileges over the target channel are needed.
The root cause highlights the danger of routing socket operations through separate logic paths without uniform authorization middleware.
Maintainers addressed this by enforcing strict validation checks inside the socket emitter helper functions.
Security researchers discovered that inconsistent validation between REST and WebSocket flows creates severe security blind spots.
Developers must ensure that every database update verifies resource ownership regardless of the entry point used.
Failing to do so allows lateral movement and data tampering within collaborative multi-tenant environments.
CVE-2026-59714 specifically targets Open WebUI deployments running versions 0.9.5 up to 0.10.0.
Upgrading immediately to version 0.10.0 or later neutralizes the vector by making channel emitters fail closed.
Audit logs in affected systems may show unexpected modifications in private chat rooms originating from standard users.
Understanding this mechanism underscores why comprehensive authorization checks must wrap every backend handler.
DailyCVE Form:
Platform: Open WebUI
Version: v0.9.5 to v0.9.9
Vulnerability : Missing Authorization
Severity: High risk
date: October 2026
Prediction: Already patched version
What Undercode Say:
To test or interact with the chat completion endpoint, attackers use standard curl commands targeting the socket routes.
curl -X POST "http://target/api/chat/completions" \
-H "Authorization: Bearer <user_token>" \
-H "Content-Type: application/json" \
-d '{"chat_id": "channel:target_victim_channel_id", "messages": [{"role": "user", "content": "injected payload"}]}'
This payload bypasses standard authorization checks by exploiting the unvalidated socket channel emitter parameter.
Exploit: (Educational Purposes!)
The exploit involves sending crafted HTTP POST requests to the chat completion endpoint with a manipulated chat ID.
The attacker authenticates with a standard low-privilege user account.
By injecting a target channel identifier into the request body, the backend forwards the message without verifying ownership.
The database emitter blindly accepts the ID and overwrites the target message slot with the provided content.
This demonstrates how broken access control in secondary pipelines leads to complete data integrity failure.
Protection: from this CVE
Administrators must immediately upgrade Open WebUI to version 0.10.0 or later where the patch is applied.
Ensure that all socket and WebSocket emitter functions perform strict server-side ownership re-validation before database commits.
Disable public registration if untrusted networks have direct access to the web interface.
Review audit logs for unusual message alterations across private chat channels.
Impact:
Successful exploitation leads to unauthorized cross-channel message overwrites and data tampering.
Attackers can inject malicious text or model error outputs into private or direct message channels they do not own.
This compromises data integrity and confidentiality within multi-tenant collaborative environments.
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Sources:
Reported By: github.com
Extra Source Hub:
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