CVE-2026-45303: Open WebUI Vulnerability Allows Script Injection

The National Vulnerability Database has detailed CVE-2026-45303, a high-severity vulnerability impacting Open WebUI, a self-hosted AI platform. Prior to version 0.6.5, the platform’s HTML rendering view was susceptible to script injection and execution. The issue stems from how Open WebUI visualizes chat content within an iFrame. While a sandbox directive was in place, it was configured with allow-scripts, allow-forms, and allow-same-origin permissions.

This permissive configuration effectively nullified the sandbox’s security benefits, granting injected scripts significant access. Attackers could execute arbitrary scripts and access the parent’s data, including local storage. The National Vulnerability Database assigned a CVSS score of 7.7 (HIGH), with a vector of CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N, highlighting the significant impact on confidentiality and integrity if exploited.

This vulnerability is a stark reminder that sandbox implementations are only as secure as their most permissive directives. Defenders running Open WebUI must prioritize upgrading to version 0.6.5 immediately. The attacker’s calculus here is straightforward: leverage a seemingly benign feature to gain broad access within the application context. For CISOs, this underscores the need for rigorous security reviews of all third-party components, even those designed for offline operation, and a deep understanding of how sandboxing attributes truly function.