CVE-2026-87012: Instance-Wide Denial of Service via Calendar Alert Metadata Type Confusion in Open WebUI
Vulnerability ID: CVE-2026-87012
CVSS Score: 4.3
Published: 2026-09-10
Open WebUI is a self-hosted AI platform. Versions 0.9.0 through 0.11.0 contain a denial-of-service vulnerability where an authenticated user can inject non-numeric values into calendar event alert metadata. The shared scheduler process fails to validate the type, leading to an unhandled TypeError that halts the execution of instance-wide alerts, suppressing notifications for all users.
TL;DR
An authenticated attacker can crash the shared Open WebUI background scheduler by sending non-numeric values in calendar event metadata, resulting in instance-wide suppression of all calendar alerts.
⚠️ Exploit Status: POC
Technical Details
- CWE ID: CWE-1287, CWE-754
- Attack Vector: Network (AV:N)
- CVSS Score: 4.3 (Medium)
- EPSS Score: 0.00268 (18.83% percentile)
- Impact: Denial of Service (Instance-wide alert suppression)
- Exploit Status: PoC concept, no public exploits
- KEV Status: Not listed in CISA KEV
Affected Systems
- Open WebUI self-hosted AI platforms
-
Open WebUI: >= 0.9.0, < 0.11.1 (Fixed in:
0.11.1)
Code Analysis
Commit: abc6900
Fix: meta is user-writable and this poll is shared by every user. Coerce non-numeric alert_minutes to None.
Mitigation Strategies
- Upgrade Open WebUI to version 0.11.1 or higher
- Implement write-path validation on API input payloads
- Sanitize database entries using SQL query to strip non-numeric alert_minutes
Remediation Steps:
- Identify running Open WebUI container
- Pull the latest official Docker image 'ghcr.io/open-webui/open-webui:v0.11.1'
- Restart the application to apply the changes
- Optionally audit database for legacy malformed calendar events
References
Read the full report for CVE-2026-87012 on our website for more details including interactive diagrams and full exploit analysis.
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