Session-token theft via post-sanitization Markdown parsing
Published May 15, 2026 · Updated May 15, 2026
Stored XSS in Open WebUI 0.3.5 through 0.8.12 allows remote authenticated users to execute JavaScript in another user's browser. Two Svelte components sanitize the raw model description before marked.parse converts a javascript URI into executable anchor markup. The attacker needs workspace.models permission, and a victim must open the model and click its link; a stolen administrator token enables account impersonation and tool-based code execution.
Summary
What happened
Stored XSS in Open WebUI 0.3.5 through 0.8.12 allows remote authenticated users to execute JavaScript in another user's browser. Two Svelte components sanitize the raw model description before marked.parse converts a javascript URI into executable anchor markup. The attacker needs workspace.models permission, and a victim must open the model and click its link; a stolen administrator token enables account impersonation and tool-based code execution.
The record
- CVE
- CVE-2026-44721
- Published
- May 15, 2026
- Updated
- May 15, 2026
- Vendor
- Open WebUI
- Product
- Open WebUI
- Classifications
- CWE-79, T1528
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- May 15, 2026CVE publishedPublication date reported by the CVE source.
- May 15, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.9.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Model-description javascript URI proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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