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Miggo AIRoot Cause AnalysisThe vulnerability, CVE-2026-87995, describes a Same-origin XSS to account takeover in Open WebUI. The root cause is explicitly stated as the PortPreview.svelte component, specifically its iframe, which hardcoded allow-same-origin in its sandbox attribute. This allowed malicious scripts served on a previewed port to execute within the application's origin and access the parent window's localStorage to steal session tokens. The provided commit 54d7a223707f03172efbb9e754db6e69709956d0 directly addresses this by modifying the sandbox attribute in src/lib/components/chat/FileNav/PortPreview.svelte. The change removes the unconditional allow-same-origin and replaces it with a conditional inclusion based on a new user setting. Therefore, the PortPreview component, specifically its rendering logic for the iframe's sandbox attribute, is the vulnerable function. When exploited, the rendering of this component would appear in a profiler's stack trace.
PortPreviewsrc/lib/components/chat/FileNav/PortPreview.svelte
| Package Name | Ecosystem | Vulnerable Versions | First Patched Version |
|---|---|---|---|
| open-webui | pip | >= 0.8.11, <= 0.11.0 | 0.11.1 |