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CVE-2026-54021 open-webui CVE debrief

CVE-2026-54021 is a vulnerability in Open WebUI, a self-hosted artificial intelligence platform. The vulnerability allows authenticated users to access unauthorized Ollama backends by manipulating the url_idx path parameter. This issue was fixed in version 0.9.6. The Common Vulnerability Scoring System (CVSS) score for this vulnerability is 6.3, indicating a medium severity level. The vulnerability was published on June 23, 2026, and last modified on June 26, 2026.

Vendor
open-webui
Product
Unknown
CVSS
MEDIUM 6.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-23
Original CVE updated
2026-06-26
Advisory published
2026-06-23
Advisory updated
2026-06-26

Who should care

Open WebUI users and administrators should be aware of this vulnerability and take necessary actions to protect their systems. Specifically, users with versions prior to 0.9.6 should upgrade to the latest version to prevent unauthorized access to Ollama backends. Additionally, users should review their system configurations and ensure that access controls are properly set up.

Technical summary

The vulnerability in Open WebUI arises from the lack of proper validation of the url_idx path parameter in several Ollama proxy routes. This allows authenticated users to access unauthorized Ollama backends, including internal, higher-privilege, or explicitly admin-disabled backends. The vulnerability has a CVSS score of 6.3 and a medium severity level. The issue was fixed in version 0.9.6, and users are advised to upgrade to the latest version.

Defensive priority

Defenders should prioritize upgrading to version 0.9.6 or later to fix the vulnerability. Additionally, defenders should review system configurations and ensure that access controls are properly set up to prevent unauthorized access to Ollama backends.

Recommended defensive actions

  • Upgrade to Open WebUI version 0.9.6 or later
  • Review system configurations and ensure proper access controls
  • Monitor system activity for suspicious behavior
  • Implement additional security measures, such as network segmentation and access controls
  • Consider compensating controls, such as web application firewalls

Evidence notes

The vulnerability was reported by an unknown source and fixed in version 0.9.6. The CVSS score for this vulnerability is 6.3, indicating a medium severity level. The vulnerability allows authenticated users to access unauthorized Ollama backends by manipulating the url_idx path parameter.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-54021 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-54021

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-54021 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-54021

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.