High severity · published Mar 12, 2026
CVE-2026-32308
OneUptime: Stored XSS via Mermaid Diagram Rendering (securityLevel: "loose")
7.6
CVSS
0.2%
EPSS
No
On KEV
Description
OneUptime is a solution for monitoring and managing online services. Prior to 10.0.23, the Markdown viewer component renders Mermaid diagrams with securityLevel: "loose" and injects the SVG output via innerHTML. This configuration explicitly allows interactive event bindings in Mermaid diagrams, enabling XSS through Mermaid's click directive which can execute arbitrary JavaScript. Any field that renders markdown (incident descriptions, status page announcements, monitor notes) is vulnerable. This vulnerability is fixed in 10.0.23.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Confidentiality
High
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 14% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ON
oneuptime · OneUptime
< 10.0.23 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-32308
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-32308
Exploit
https://github.com/OneUptime/oneuptime/security/advisories/GHSA-wvh5-6vjm-23qh
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