# CVE-2026-109298: Open WebUI regex denial of service in file search tools

Source: https://junglewise.ai/threats/cve-2026-109298-open-webui-0-11-0-before-0-11-4-compiles-user-chosen-grep  
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-2026-109298 · Severity: medium · CVSS 6.5 · Published 2026-10-12

Open WebUI is a web interface for AI models that includes file search tools. Authenticated users can craft malicious regex patterns that cause the application to consume excessive memory and CPU during pattern compilation, blocking other users from accessing the service and potentially crashing the application.

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-2026-109298 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-109298 being exploited in the wild.

**How severe is CVE-2026-109298?** 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-2026-109298?** Yes: fixed in 0.11.4. Until then: Upgrading to 0.11.4 is sufficient; no operator configuration is required. The fix constrains regex compilation with RE2 engine limits and pattern length caps.</anigation>
<parameter name="timeline">[{"kind":"disclosed","at":"2026-09-27"},{"kind":"patched","at":"2026-09-21","note":"Commit 97e013a released in version 0.11.4"}] Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-109298 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-109298?** 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 0.11.4 is sufficient; no operator configuration is required. The fix constrains regex compilation with RE2 engine limits and pattern length caps.</anigation>
<parameter name="timeline">[{"kind":"disclosed","at":"2026-09-27"},{"kind":"patched","at":"2026-09-21","note":"Commit 97e013a released in version 0.11.4"}]

## Technical details

The vulnerability exists in the pattern compiler for the grep_knowledge_files and grep_chat_files tools, which compile user-supplied regex patterns without bounds. The regex engine expands nested counted repetitions at compile time, allowing short patterns with nested repetition counts (e.g., `(a+)+` with high counts) to allocate hundreds of megabytes. Compiled patterns are cached for the process lifetime, and the compilation work blocks the event loop synchronously, affecting all users on affected workers.

## Affected products

- Open WebUI Open WebUI 0.11.0 through 0.11.3

## References

- [https://github.com/open-webui/open-webui/commit/97e013a66169c4fcd7f26ab9e41a4ff260ffd4da](https://github.com/open-webui/open-webui/commit/97e013a66169c4fcd7f26ab9e41a4ff260ffd4da)
- [https://github.com/open-webui/open-webui/security/advisories/GHSA-gww9-mhgj-pfqh](https://github.com/open-webui/open-webui/security/advisories/GHSA-gww9-mhgj-pfqh)

## 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 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)
- [Open WebUI regular expression denial of service in file search](https://junglewise.ai/threats/cve-2026-109295-open-webui-from-0-11-0-before-0-11-4-contains-a-regular)