What is the CVSS score of CVE-2026-21855?

CVE-2026-21855 has a CVSS 3.1 base score of 9.3 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N. EPSS exploitation probability: 0.0%.

Which versions of Tarkov Data Manager are affected by CVE-2026-21855?

Organizations using Tarkov Data Manager face critical risk from CVE-2026-21855, a cross-site scripting vulnerability rated CVSS 9.3.

Is there a public PoC exploit available for CVE-2026-21855?

Yes, a public proof-of-concept exploit is available for CVE-2026-21855. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-21855?

Within 24 hours: Identify all affected systems and apply vendor patches immediately. Verify anti-CSRF tokens and content security policies are enforced.

Tarkov Data Manager CVE-2026-21855

CRITICAL

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

2026-01-07 security-advisories@github.com

XSS Tarkov Data Manager Tarkov

9.3

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

9.3 CRITICAL

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

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

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

High

Integrity

High

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

PoC Detected

Feb 03, 2026 - 16:20 vuln.today

Public exploit code

CVE Published

Jan 07, 2026 - 19:15 nvd

CRITICAL 9.3

DescriptionGitHub Advisory

The Tarkov Data Manager is a tool to manage the Tarkov item data. Prior to 02 January 2025, a reflected Cross Site Scripting (XSS) vulnerability in the toast notification system allows any attacker to execute arbitrary JavaScript in the context of a victim's browser session by crafting a malicious URL. A series of fix commits on 02 January 2025 fixed this and other vulnerabilities.

AnalysisAI

Tarkov Data Manager has reflected XSS in the toast notification system. Attackers can craft URLs that execute arbitrary JavaScript in the victim's browser, stealing session tokens. PoC available, fixed in January 2025.

Technical ContextAI

The toast notification system renders user-controlled URL parameters without sanitization (CWE-79). Combined with the scope change (S:C), the XSS can access data from other origins if the application uses shared session cookies or cross-origin communication.