CVE-2026-54011 json
Open WebUI: Stored XSS in Mermaid Markdown Preview
published 2026-06-17 4 mo ago modified 2026-07-20 3 mo ago also GHSA-v8qj-hxv7-mgvv , PYSEC-2026-2759 , EUVD-2026-38531
- cvss
- 8.7
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 27%
- public exploits
- 0
- none known
Summary
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.6,Open WebUI renders Mermaid blocks from Markdown files in the file preview panel and inserts the generated SVG into the DOM using innerHTML. Because Mermaid is configured with securityLevel: 'loose', attacker-controlled Mermaid content can be rendered unsafely in this flow. A working payload was validated through the Markdown preview path, resulting in JavaScript execution in the victim’s browser under the application origin. This vulnerability is fixed in 0.9.6.
Patch / fix
- pypi open-webui 0.9.6
- openwebui open_webui 0.9.6
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- total
- Assessed
- 4 mo ago
Exploit prediction
0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/open-webui/open-webui/security/advisories/GHSA-v8qj-hxv7-mgvv referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N |
| NVD | 3.1 | 5.4 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N |
| OSV | 3.1 | 8.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N |
| GitHub | 3.1 | 8.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | open-webui | <0.9.6 |
0.9.6 |
Affected products
- open-webui open-webui
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
github.com
/open-webui/open-webui/security/advisories/GHSA-v8qj-hxv7-mgvv
exploit, web, mitigation, vendor-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-54011
advisory
-
github.com
/advisories/GHSA-v8qj-hxv7-mgvv
advisory
-
github.com
/open-webui/open-webui
package
-
github.com
/pypa/advisory-database/tree/main/vulns/open-webui/PYSEC-2026-2759.yaml
web
-
pypi.org
/project/open-webui
web, package
Sources
- CVE List CVE-2026-54011
- GitHub Advisory GHSA-v8qj-hxv7-mgvv
- NVD CVE-2026-54011
- OSV PYSEC-2026-2759
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.