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CVE-2026-28788— Open WebUI's process_files_batch() endpoint missing ownership check, allows unauthorized file overwrite

Quick assessment

Affected
open-webui open-webui
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Open WebUI是Open WebUI开源的一个可扩展、功能丰富、用户友好的自托管 WebUI。 Open WebUI 0.8.6之前版本存在安全漏洞，该漏洞源于/api/v1/retrieval/process/files/batch端点缺少所有权检查，可能导致任意文件内容被覆盖。

CVSS 7.1 · High EPSS 0.38% · P30
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I. Basic Information for CVE-2026-28788

Vulnerability Information
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Vulnerability Title
Open WebUI's process_files_batch() endpoint missing ownership check, allows unauthorized file overwrite
Source: CVE Program / CVE List V5
Vulnerability Description
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to version 0.8.6, any authenticated user can overwrite any file's content by ID through the `POST /api/v1/retrieval/process/files/batch` endpoint. The endpoint performs no ownership check, so a regular user with read access to a shared knowledge base can obtain file UUIDs via `GET /api/v1/knowledge/{id}/files` and then overwrite those files, escalating from read to write. The overwritten content is served to the LLM via RAG, meaning the attacker controls what the model tells other users. Version 0.8.6 patches the issue.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
通过用户控制密钥绕过授权机制
Source: CVE Program / CVE List V5
Vulnerability Title
Open WebUI 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Open WebUI是Open WebUI开源的一个可扩展、功能丰富、用户友好的自托管 WebUI。 Open WebUI 0.8.6之前版本存在安全漏洞，该漏洞源于/api/v1/retrieval/process/files/batch端点缺少所有权检查，可能导致任意文件内容被覆盖。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
open-webui open-webui < 0.8.6 -

II. Public POCs for CVE-2026-28788

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III. Intelligence Information for CVE-2026-28788

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Same Patch Batch · open-webui · 2026-03-26 · 4 CVEs total

CVE-2026-29070 5.4 MEDIUM Open WebUI has unauthorized deletion of knowledge files
CVE-2026-28786 4.3 MEDIUM Open WebUI vulnerable to Path Traversal in `POST /api/v1/audio/transcriptions`
CVE-2026-29071 3.1 LOW Open WebUI's Insecure Direct Object Reference (IDOR) allows access to other users' memorie

IV. Related Vulnerabilities

Same product: open-webui
Same vendor: open-webui
Same weakness: CWE-639

V. Comments for CVE-2026-28788

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