Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.6.5, through the HTML rendering view, scripts can be injected and executed. The frontend provides a function to visualize the HTML content of a current chat. The content is embedded in an iFrame with the allow-scripts allow-forms allow-same-origin sandbox directive. This means that the content is placed in a sandbox but with permission to execute scripts and access the parent’s data (e.g., local storage). As a result, only a few functions are restricted (e.g., displaying an alert box), but in effect, the sandbox attribute is largely nullified. This vulnerability is fixed in 0.6.5.
CVE-2026-45303
HIGHNVD 7.77.7—Elevated
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.7 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 88% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.7
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.7Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.7
- EG Score
- 7.7(medium)
- EPSS
- 12.1%
- KEV
- Not listed
Published
May 15, 2026
Last Modified
May 19, 2026
Advisory Details (1)
Auto-updated May 18, 2026🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available
Stored XSS via the HTML renedering view · Advisory · open-webui/open-webui · GitHub
https://github.com/open-webui/open-webui/security/advisories/GHSA-4vrc-m9ch-6m3rVendor Advisories for CVE-2026-45303(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| open-webui | 0.1.124 ... 0.6.4 (95 versions) | 0.6.5 | — |
Frequently asked(5)
What is CVE-2026-45303?
CVE-2026-45303 is a high vulnerability published on May 15, 2026. Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.6.5, through the HTML rendering view, scripts can be injected and executed. The frontend provides a function to visualize the HTML content of a current chat. The content is embedded in an…
When was CVE-2026-45303 disclosed?
CVE-2026-45303 was first published in the National Vulnerability Database on May 15, 2026, with the most recent update on May 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45303 actively exploited?
CVE-2026-45303 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 12.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-45303?
CVE-2026-45303 has a CVSS v3 base score of 7.7 (NVD).
How do I remediate CVE-2026-45303?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45303, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-45303
Is Your Infrastructure Affected by CVE-2026-45303?
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