CVE-2026-74234Network attack vector

Script execution via Mermaid front-matter eval

Published Aug 17, 2026 · Updated Aug 17, 2026

Cross-site scripting in Legora before 2026-08-14 allows attackers to execute arbitrary JavaScript via crafted Mermaid content. A Mermaid block parser processes gray-matter JavaScript front matter with eval() before SVG sanitization, so untrusted directives run in the page origin instead of being neutralized before rendering. Exploitation requires the ability to place or influence Mermaid diagram content and a victim to view the rendered output; on Word and Outlook add-ins, scripts can reach bearer tokens stored in localStorage.

CVSS severity5.1
Medium
EPSS probabilityUnavailable
No score available in this record
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Cross-site scripting in Legora before 2026-08-14 allows attackers to execute arbitrary JavaScript via crafted Mermaid content. A Mermaid block parser processes gray-matter JavaScript front matter with eval() before SVG sanitization, so untrusted directives run in the page origin instead of being neutralized before rendering. Exploitation requires the ability to place or influence Mermaid diagram content and a victim to view the rendered output; on Word and Outlook add-ins, scripts can reach bearer tokens stored in localStorage.

The record

CVE
CVE-2026-74234
Published
Aug 17, 2026
Updated
Aug 17, 2026
Vendor
Legora
Product
Legora
Classifications
CWE-95, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 17, 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=0 <2026-08-14

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Legora · Legoraversion=0 <2026-08-14

Published CVSS scores

5.1VulnCheckCVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
5.1GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-95Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
T1059.007Command and Scripting Interpreter: JavaScript

Public exploit references

No public exploit references are available in this record.

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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