What is the CVSS score of CVE-2026-27639?

CVE-2026-27639 has a CVSS 3.1 base score of 5.4 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Mercator are affected by CVE-2026-27639?

Organizations using Mercator should be aware of moderate risk from CVE-2026-27639, a cross-site scripting vulnerability rated CVSS 5.4.. A patch is available.

How to fix or mitigate CVE-2026-27639?

Within 30 days: Identify affected systems running Mercator and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

Mercator CVE-2026-27639

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2026-02-25 security-advisories@github.com

XSS Mercator

5.4

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

5.4 MEDIUM

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

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:55 vuln.today

Patch released

Feb 27, 2026 - 18:45 nvd

Patch available

CVE Published

Feb 25, 2026 - 04:16 nvd

MEDIUM 5.4

DescriptionGitHub Advisory

Mercator is an open source web application designed to enable mapping of information systems. A stored Cross-Site Scripting (XSS) vulnerability exists in Mercator prior to version 2026.02.22 due to the use of unescaped Blade directives ({!! !!}) in display templates. An authenticated user with the User role can inject arbitrary JavaScript payloads into fields such as "contact point" when creating or editing entities. The payload is then executed in the browser of any user who views the affected page, including administrators. Version 2026.02.22 fixes the vulnerability.

AnalysisAI

Stored XSS in Mercator prior to version 2026.02.22 allows authenticated users to execute arbitrary JavaScript in other users' browsers by injecting malicious payloads into entity fields like contact points. The vulnerability exploits improperly escaped Blade template directives, enabling attackers to compromise administrator accounts and perform actions with their privileges. A patch is available in version 2026.02.22.

Technical ContextAI

Classified as CWE-79 (Cross-site Scripting (XSS)). Affects Mercator. Mercator is an open source web application designed to enable mapping of information systems. A stored Cross-Site Scripting (XSS) vulnerability exists in Mercator prior to version 2026.02.22 due to the use of unescaped Blade directives ({!! !!}) in display templates. An authenticated user with the User role can inject arbitrary JavaScript payloads into fields such as "contact point" when creating or editing entities. The payload is then executed in the browser of any user who views the affecte

RemediationAI

A vendor patch is available — apply it immediately. Implement output encoding and Content Security Policy headers. Restrict network access to the affected service where possible.