CVE-2026-32308Public exploitNetwork attack vector

Stored XSS via unsanitized Mermaid SVG injection

Published Mar 12, 2026 · Updated Mar 12, 2026

Stored XSS in OneUptime before 10.0.23 allows remote authenticated users to execute JavaScript when another user views crafted Markdown. MarkdownViewer enables Mermaid's loose security mode and assigns rendered SVG containing click handlers directly to innerHTML without sanitization. An account able to write a Markdown-rendered field and a viewer interaction are required, exposing the viewer's application-session data to script access.

CVSS severity7.6
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in OneUptime before 10.0.23 allows remote authenticated users to execute JavaScript when another user views crafted Markdown. MarkdownViewer enables Mermaid's loose security mode and assigns rendered SVG containing click handlers directly to innerHTML without sanitization. An account able to write a Markdown-rendered field and a viewer interaction are required, exposing the viewer's application-session data to script access.

The record

CVE
CVE-2026-32308
Published
Mar 12, 2026
Updated
Mar 12, 2026
Vendor
OneUptime
Product
OneUptime
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 12, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 12, 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.

  1. Affected versionversion=< 10.0.23

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

OneUptime · OneUptimeversion=< 10.0.23

Published CVSS scores

7.6GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

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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