Legora < 2026-08-14 XSS via Mermaid gray-matter JavaScript Engine

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74234
StatePUBLISHED
AssignerVulnCheck
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-17 20:16:46 UTC
Updated2026-08-17 20:16:46 UTC
DescriptionLegora before 2026-08-14 contains a cross-site scripting vulnerability that allows attackers to achieve arbitrary JavaScript execution in a victim's browser by embedding a Mermaid block prefixed with a gray-matter JavaScript front-matter directive, causing the front-matter parser to invoke eval() before any SVG sanitization occurs. Attackers can exploit this flaw through influenced Mermaid diagram content to execute arbitrary JavaScript in the user's browser context, with elevated impact on Word and Outlook add-in surfaces where bearer session tokens are persisted in localStorage.

Risk And Classification

Primary CVSS: v4.0 5.1 MEDIUM from [email protected]

CVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-95 | CWE-95 Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary5.1MEDIUMCVSS: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/C...
4.0CNACVSS5.1MEDIUMCVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
3.1[email protected]Primary7.7HIGHCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N
3.1CNACVSS7.7HIGHCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
High
Attack Requirements
None
Privileges Required
Low
User Interaction
Passive
Confidentiality
None
Integrity
None
Availability
None
Sub Conf.
High
Sub Integrity
High
Sub Availability
None

CVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Legora Legora affected 2026-08-14 date Not specified

References

ReferenceSourceLinkTags
www.vulncheck.com/advisories/legora-2026-08-14-xss-via-mermaid-gray-matter-java... [email protected] www.vulncheck.com
legora.com [email protected] legora.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Mobasi Security Team (en)

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report