# CVE-2026-109295: Open WebUI regular expression denial of service in file search

Source: https://junglewise.ai/threats/cve-2026-109295-open-webui-from-0-11-0-before-0-11-4-contains-a-regular  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-12. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-109295 · Severity: medium · CVSS 6.5 · Published 2026-10-12

Open WebUI is a web interface for interacting with AI models. Authenticated users can submit specially crafted regex patterns to the file search feature that cause the server to freeze for about 2 seconds per request, making it unavailable to other users. An attacker can repeat these calls to persistently disrupt service.

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

## Quick answers

**Is CVE-2026-109295 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-109295 being exploited in the wild.

**How severe is CVE-2026-109295?** Medium severity, with a CVSS score of 6.5, published 12 October 2026.

**Which products and versions are affected?** Open WebUI 0.11.0 through 0.11.3.

**Is there a fix for CVE-2026-109295?** Yes: fixed in 0.11.4. Until then: Upgrading to version 0.11.4 or later is required; the fix moves file search operations off the event loop into worker threads and switches regex matching to the RE2 engine, which cannot backtrack catastrophically. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-109295 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-109295?** Check whether you run Open WebUI 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

- Fixed in 0.11.4

Upgrading to version 0.11.4 or later is required; the fix moves file search operations off the event loop into worker threads and switches regex matching to the RE2 engine, which cannot backtrack catastrophically.

## Technical details

A regular expression denial of service (ReDoS) vulnerability exists in the grep_knowledge_files and grep_chat_files tools, which accept user-supplied regex patterns. The vulnerable code runs synchronous pattern matching directly on the event loop with a 2-second timeout, blocking the entire worker from servicing other requests while the regex catastrophically backtracks. Authenticated users without elevated privileges can exploit this by instructing the model to call these functions with malicious patterns like (a|a)+$.

## Affected products

- open-webui Open WebUI 0.11.0 through 0.11.3

## Timeline

- 2026-09-27: disclosed
- 2026-10-12: advisory
- 2026-10-12: patched

## References

- [https://github.com/open-webui/open-webui/security/advisories/GHSA-gfjp-5hc9-852r](https://github.com/open-webui/open-webui/security/advisories/GHSA-gfjp-5hc9-852r)
- [https://www.vulncheck.com/advisories/open-webui-0.11.0-before-0.11.4-redos-via-grep-knowledge-files-event-loop](https://www.vulncheck.com/advisories/open-webui-0.11.0-before-0.11.4-redos-via-grep-knowledge-files-event-loop)

## Related threats

- [Open WebUI stored cross-site scripting in Markdown renderer](https://junglewise.ai/threats/cve-2026-109300-open-webui-from-0-6-31-before-0-11-4-contains-a-stored-cross)
- [Open WebUI denial of service in recurrence rule validation](https://junglewise.ai/threats/cve-2026-109299-open-webui-from-0-9-0-before-0-11-4-contains-a-denial-of-service)
- [Open WebUI regex denial of service in file search tools](https://junglewise.ai/threats/cve-2026-109298-open-webui-0-11-0-before-0-11-4-compiles-user-chosen-grep)
- [Open WebUI automation recurrence-rule denial of service](https://junglewise.ai/threats/cve-2026-109297-open-webui-0-11-0-before-0-11-4-contains-a-denial-of-service)
- [Open WebUI missing authorization in model provider routes](https://junglewise.ai/threats/cve-2026-109296-open-webui-before-0-11-4-contains-a-missing-authorization)