CVE-2026-88000

Open WebUI: Any authenticated user can hang the server via message deletion in a cyclic chat tree

Published Sep 9, 2026 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Description

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.10.0 until 0.11.1, DELETE /api/v1/chats/{id}/messages/{message_id} used the chat-history deletion helper in backend/open_webui/models/chats.py to follow childrenIds without recording visited message identifiers. An authenticated user could store a cyclic chat tree and delete a message, causing a synchronous infinite loop on the server request loop that blocked every user's requests until the process was killed. This issue is fixed in version 0.11.1.

Analysis

Technical impact

A flaw in Open WebUI’s chat message deletion endpoint allowed an authenticated user to cause the server to enter a synchronous infinite loop. The defect existed between versions 0.10.0 and 0.11.1 when the deletion helper traversed child message identifiers without recording if a node had already been visited. Triggering the loop by deleting a message in a cyclic chat tree would stall all requests handled by the process until it crashed or was restarted, effectively denying service to all users.

Affected Systems

The vulnerability affects the open-webui open-webui product, specifically the versions from 0.10.0 through 0.11.1 inclusive. The issue was resolved in release 0.11.1, so any installations on those vulnerable versions are at risk.

Risk and Exploitability

The flaw carries a CVSS score of 6.5, indicating a moderate severity. The EPSS score is unavailable, and the vulnerability is not listed in CISA’s KEV catalog. Exploitation requires an authenticated user with access to delete messages; thus the attack vector is an authenticated API call. Once triggered, the effect is a server hang that blocks all user activity until the process is killed.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

open-webui

affected

Version	Status	Constraints
`>= 0.10.0, < 0.11.1`	affected	—

Configuration 1 [-]

cpe:2.3:a:openwebui:open_webui:*:*:*:*:*:*:*:*

No data.

Vendor Product Versions

Open-webui

Version	Status	Scheme	Platform
`[0.10.0,0.11.1)`	affected	semver	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade Open WebUI to version 0.11.1 or later.
If an upgrade cannot be performed immediately, block the DELETE /api/v1/chats/{id}/messages/{message_id} endpoint for authenticated users until the patch is applied.
Audit existing chat data to identify and remove any cyclic trees that could trigger the infinite loop.

Generated by OpenCVE AI on September 9, 2026 at 22:20 UTC.

Tracking

Advisories

Source	ID	Title
Github GHSA	GHSA-3cgp-3cqx-j8w2	Open WebUI: Any authenticated user can hang the server via message deletion in a cyclic chat tree

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.592% probability within 30 days)

Exploitation poc

Automatable no

Technical Impact partial

References

Link	Providers
https://github.com/open-webui/open-webui/commit/b933292d63d12be3fd1416fe55519ddc7aa336bc
https://github.com/open-webui/open-webui/pull/28035
https://github.com/open-webui/open-webui/releases/tag/v0.11.1
https://github.com/open-webui/open-webui/security/advisories/GHSA-3cgp-3cqx-j8w2

History

Sep 14, 2026 9:00 PM First appearance in the feed. Affected versions updated. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Openwebui Openwebui open Webui
CPEs		cpe:2.3:a:openwebui:open_webui::::::::
Vendors & Products		Openwebui Openwebui open Webui

Sep 10, 2026 6:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Sep 10, 2026 11:15 AM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Open-webui Open-webui open-webui
Vendors & Products		Open-webui Open-webui open-webui

Sep 9, 2026 9:45 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.10.0 until 0.11.1, DELETE /api/v1/chats/{id}/messages/{message_id} used the chat-history deletion helper in backend/open_webui/models/chats.py to follow childrenIds without recording visited message identifiers. An authenticated user could store a cyclic chat tree and delete a message, causing a synchronous infinite loop on the server request loop that blocked every user's requests until the process was killed. This issue is fixed in version 0.11.1.
Title		Open WebUI: Any authenticated user can hang the server via message deletion in a cyclic chat tree
Weaknesses		CWE-835
References		https://github.com/open-webui/open-webui/commit/b933292d63d12be3fd1416fe55519ddc7aa336bc https://github.com/open-webui/open-webui/pull/28035 https://github.com/open-webui/open-webui/releases/tag/v0.11.1 https://github.com/open-webui/open-webui/security/advisories/GHSA-3cgp-3cqx-j8w2
Metrics		cvssV3_1 `{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}`