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NVD / CVE Program· CNA GitHub_M

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

HighCVSS 7.1 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 29/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 2.9% (FIRST EPSS); higher than 87.4% of all records.
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: open-webui (PyPI) 0.8.6.

Low priority for now. Upgrade to open-webui (PyPI) 0.8.6 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

Published
Mar 26, 2026
Updated
Jun 17, 2026
EPSS
2.9% · 87th percentile

Report tools

JSON

Action score

29

Monitor

Low priority for now.

CVSS
28 / 40 · 7.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.9%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
7.1
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-28788

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
openwebuiopen webui

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • open-webui open-webui

    • < 0.8.6affected

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • openwebui open webuibefore 0.8.6

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
PyPIopen-webuibefore 0.8.60.8.6

Same product

openwebui: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-44566Open WebUI: Arbitrary File Upload and Path Traversal
    39Monitor
  • CVE-2026-56400open-webui - Remote Code Execution via CORS Misconfiguration and Session Validation
    36Monitor
  • CVE-2026-59216Open WebUI: Cross-user code-interpreter and tool execution via unvalidated Socket.IO event-caller session_id
    36Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-26193Feb 19, 2026 · Open WebUI vulnerable to Stored XSS via iFrame embeds in response messages
    21Monitor
  • ← EarlierCVE-2026-28786Mar 26, 2026 · Open WebUI vulnerable to Path Traversal in `POST /api/v1/audio/transcriptions`
    17Monitor
  • Later →CVE-2026-29070Mar 26, 2026 · Open WebUI has unauthorized deletion of knowledge files
    32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
PyPI:open-webui0.8.6Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-4457050 days apartOpen WebUI: Inconsistent authorization controls within memories API
    33Monitor
  • CVE-2026-4540250 days apartOpen WebUI: Cross-User File Access via Unchecked file_id in Folder Knowledge and Knowledge-Base Attach Endpoints
    32Monitor
  • CVE-2026-4567150 days apartOpen WebUI: shared-chat branch ignores access_type, allowing unauthorized file deletion
    32Monitor
  • CVE-2026-4539850 days apartOpen WebUI: IDOR - Retrieval API Bypasses Knowledge Base Access Controls
    30Monitor
  • CVE-2026-4534950 days apartOpen WebUI: Broken Access Control for Completions API
    28Monitor
  • CVE-2026-4566650 days apartOpen WebUI: Indirect Object Reference (IDOR) in user notes
    26Monitor

Not on record for this CVE: patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
high · data or configuration can be modified
Availability
low · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
High
Availability impact
Low

Weakness class (CWE)

CWE-639 · Authorization Bypass Through User-Controlled Key

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L

nvd-secondary

Root cause

The endpoint fetches the record by the ID sent in the request, but never checks whether the record belongs to the requesting user.

The bug in code

The whole CWE-639 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
const invoice = await Invoice.findById(req.params.id);res.json(invoice);

Fixed

ts
const invoice = await Invoice.findOne({  id: req.params.id,  ownerId: req.user.id,});if (!invoice) return res.sendStatus(404);res.json(invoice);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

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