by Kastro
Paper/Archive/CVE-2026-56398

CVE-2026-56398

open-webui open-webui — Open WebUI - Stored Cross-Site Scripting via OAuth Picture Claim SVG Data URI

EPSS 0.6%CVSS 9.0
critical.is priorityof 100
37
CVSS 9.0 (NVD)9.0 / 10 × 3027.0Not in CISA KEV+300.0EPSS percentile 50.4.504 × 2010.1No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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

ProductAffectedFixed inSource
open-webui< 0.9.50.9.5CNA

Scores by source

NVD9.0CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
VulnCheck (CNA)8.5CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
VulnCheck (CNA)7.3CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
CISA ADPSSVCExploitation: none · Automatable: no · Technical impact: partial

References

advisorygithub.com/open-webui/open-webui/security/advisories/GHSA-3wgj-c2hg-vm6qwriteupvulncheck.com/advisories/open-webui-stored-cross-site-scripting-via-oauth-picture-claim-svg-data-uri