# CVE-2026-87012: Open WebUI calendar alert suppression via non-numeric meta value

Source: https://junglewise.ai/threats/cve-2026-87012-open-webui-calendar-alert-suppression-via-non-numeric-meta-value  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-09. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-87012 · Severity: medium · CVSS 4.3 · Published 2026-09-09

Open WebUI is a web-based platform for managing chat, automations, and calendar events. An authenticated regular user can disable calendar alerts for all users on the instance by storing a text string instead of a number in a calendar event's alert configuration. The impact is limited to calendar alert functionality—notifications fail to send for roughly an hour per malicious event—but affects all users simultaneously and can be sustained indefinitely.

Technologies: [open-webui (PyPI)](https://junglewise.ai/threats/technologies/open-webui). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-87012 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-87012 being exploited in the wild.

**How severe is CVE-2026-87012?** Medium severity, with a CVSS score of 4.3, published 9 September 2026.

**Which products and versions are affected?** open-webui (PyPI) >= 0.9.0, < 0.11.1, ECOSYSTEM:introduced=0.9.0,fixed=0.11.1.

**Is there a fix for CVE-2026-87012?** Yes. open-webui (PyPI): upgrade to 0.11.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-87012 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-87012?** Check whether you run open-webui (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- open-webui (PyPI): upgrade to 0.11.1 or later

  ```sh
  pip install "open-webui>=0.11.1"
  ```


## Technical details

The vulnerability is a type confusion and missing input validation issue (CWE-1287, CWE-754) in Open WebUI's calendar event model. Calendar events carry a free-form `meta` dictionary stored without type enforcement. The scheduler's alert pass reads the alert offset from this dictionary and performs numeric comparison without type-checking, assuming prior validation. When a user stores a string (e.g., `"5"`) instead of a numeric value, the scheduler raises a type error mid-pass, aborting the entire instance-wide alert check. This affects all users regardless of permissions. The attack requires: (1) calendar enabled, (2) attacker with calendar feature permission (default for all users), and (3) event start within the one-hour lookahead window. No admin, shared calendars, or recurrence rules are required. Fixed in version 0.11.1 (PR #28790) by treating non-numeric alert values as unset and falling back to defaults; events already holding bad values revert automatically.

## Affected products

- Open WebUI Contributors Open WebUI >= 0.9.0, < 0.11.1

## Identifiers

- CVE-2026-87012
- GHSA-v39v-59xw-j98g
- PYSEC-2026-4126

## Timeline

- 2026-09-04: disclosed
- 2026-09-10: advisory
- 2026-09-04: patched: Fix released in version 0.11.1, PR #28790

## References

- [https://api.github.com/users/DshtAnger](https://api.github.com/users/DshtAnger)
- [https://github.com/DshtAnger](https://github.com/DshtAnger)
- [https://api.github.com/users/DshtAnger/gists%7B/gist_id%7D](https://api.github.com/users/DshtAnger/gists%7B/gist_id%7D)
- [https://api.github.com/users/DshtAnger/repos](https://api.github.com/users/DshtAnger/repos)
- [https://avatars.githubusercontent.com/u/14113449?v=4](https://avatars.githubusercontent.com/u/14113449?v=4)
- [https://api.github.com/users/DshtAnger/events%7B/privacy%7D](https://api.github.com/users/DshtAnger/events%7B/privacy%7D)

## Related threats

- [Open WebUI OAuth token exchange authorization bypass](https://junglewise.ai/threats/cve-2026-88006-open-webui-oauth-token-exchange-authorization-bypass)
- [Open WebUI OAuth token exchange authorization bypass](https://junglewise.ai/threats/cve-2026-88005-open-webui-oauth-token-exchange-authorization-bypass)
- [Open WebUI infinite loop denial of service in chat history reconstruction](https://junglewise.ai/threats/cve-2026-88002-open-webui-infinite-loop-denial-of-service-in-chat-history)
- [Open WebUI server-side request forgery via unvalidated HTTP redirects](https://junglewise.ai/threats/cve-2026-88001-open-webui-server-side-request-forgery-via-unvalidated-http)
- [Open WebUI denial of service via cyclic chat tree message deletion](https://junglewise.ai/threats/cve-2026-88000-open-webui-denial-of-service-via-cyclic-chat-tree-message)