CVE-2026-56398

HIGH
Published Jul 15, 2026 Modified Jul 16, 2026 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.

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CVSS v3.1 Score

7.3
HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0034
Probability of exploitation
0.26%
Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-20 Improper Input Validation

Affected Products

Vendor Product
openwebui open_webui

References

Frequently Asked Questions

What is CVE-2026-56398? +
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. It has a CVSS v3.1 base score of 7.3 (HIGH).
How severe is CVE-2026-56398? +
CVE-2026-56398 has a CVSS v3.1 score of 7.3 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0034, placing it in the 0th percentile for exploitation probability.
What products are affected by CVE-2026-56398? +
CVE-2026-56398 affects products from openwebui, specifically: open_webui. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2026-56398? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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