What’s Vulnerable › Vulnerabilities

CVE-2026-56398: Open WebUI - Stored Cross-Site Scripting via OAuth Picture Claim SVG Data URI

• Severity: critical (CVSS 9.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-07-15 · updated 2026-07-16
• Weakness: CWE-20

Description

Open WebUI before 0.9.5 contains a stored cross-site scripting vulnerability in the OAuth authentication flow where the picture claim URL MIME type is inferred from file extension rather than Content-Type header, allowing SVG files to bypass the profile image validator and be stored as data URIs. Authenticated users who visit the profile image endpoint receive attacker-controlled SVG content with inline disposition and no default security headers, enabling script execution in the same origin to steal authentication tokens and achieve account takeover.

Affected products

• open-webui: before 0.9.5 — fixed in 0.9.5

How to fix

Upgrade to a fixed version: open-webui 0.9.5. Check the vendor advisory for mitigations.

References

• https://github.com/open-webui/open-webui/security/advisories/GHSA-3wgj-c2hg-vm6q
• https://www.vulncheck.com/advisories/open-webui-stored-cross-site-scripting-via-oauth-picture-claim-svg-data-uri

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