CVE-2026-56398 | Open WebUI before 0.9.5 contains a stored cross-site scripti… | CVSS 7.3 HIGH

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.

Metadata

CVE ID: CVE-2026-56398
State: PUBLISHED
Assigner: VulnCheck
Reserved: 2026-06-21 12:37 UTC
Published: 2026-07-15 11:25 UTC
Last updated: 2026-07-15 13:25 UTC
Primary CWE: CWE-20
Improper Input Validation
Vendor / Product: open-webui / open-webui
Sources: cve.org · NVD

Severity & Metrics

7.3 HIGH CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

SSVC — CISA Coordinator

Exploitation: none
Automatable: no
Tech. Impact: partial

Affected products (1)

Vendor	Product	Platform	Versions
open-webui	open-webui	—	0 < 0.9.5, 0.9.5

Weakness (CWE)

CWE	Source	Description
CWE-20	cna	Improper Input Validation

CVSS scores (2)

Score	Severity	Version	Source	Vector
8.5	HIGH	4.0	cna	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
7.3	HIGH	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

References (2)

GitHub Security Advisory (GHSA-3wgj-c2hg-vm6q) https://github.com/open-webui/open-webui/security/advisories/GHSA-3wgj-c2hg-vm6q
VulnCheck Advisory: Open WebUI - Stored Cross-Site Scripting via OAuth Picture Claim SVG Data URI https://www.vulncheck.com/advisories/open-webui-stored-cross-site-scripting-via-oauth-picture-claim-svg-data-uri