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CVE-2026-28788

Openwebui Open Webui broken access control

7.1 HIGHPublic exploitEPSS 0.38%
  1. Published26 Mar 2026

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredLow
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityHigh
AvailabilityLow
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L

Affected products

Openwebui Open Webui< 0.8.6

Remediation

Fixed in
Openwebui Open Webui≥ 0.8.6

References

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Frequently asked

Is CVE-2026-28788 being actively exploited?

CVE-2026-28788 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.38%.

How severe is CVE-2026-28788?

CVE-2026-28788 has a CVSS 3.1 base score of 7.1, rated high. EPSS estimates a 0.38% probability of exploitation.

Which products are affected by CVE-2026-28788?

Affected products include Openwebui Open Webui.

How do I fix CVE-2026-28788?

Upgrade affected software to a fixed version, for example Openwebui Open Webui 0.8.6 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-28788 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.