🛡️ CVE-2026-21868
🟠 CVSS 7.5 — High ✅ No Known Exploit CWE-1333 NVD
7.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Flag Forge is a Capture The Flag (CTF) platform. Versions 2.3.2 and below have a Regular Expression Denial of Service (ReDoS) vulnerability in the user profile API endpoint (/api/user/[username]). The application constructs a regular expression dynamically using unescaped user input (the username parameter). An attacker can exploit this by sending a specially crafted username containing regex meta-characters (e.g., deeply nested groups or quantifiers), causing the MongoDB regex engine to consume excessive CPU resources. This can lead to Denial of Service for other users. The issue is fixed in version 2.3.3. To workaround this issue, implement a Web Application Firewall (WAF) rule to block requests containing regex meta-characters in the URL path.

Details

Severity HIGH
CVSS Score 7.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE CWE-1333
Public Exploit ✅ No
Source NVD
Published 2026-01-08
Updated 2026-06-02
Modified 2026-01-20
Fix URL N/A

Affected Packages

Software From version Fixed in
flagforge 2.0 2.3.3

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