CVE-2026-21868

Source
https://cve.org/CVERecord?id=CVE-2026-21868
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-21868.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-21868
Aliases
  • GHSA-949h-9824-xmcx
Published
2026-01-08T00:26:46.668Z
Modified
2026-03-13T04:03:18.847208Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
Flag Forge has ReDoS Vulnerability in User Profile Lookup API
Details

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.

Database specific
{
    "cwe_ids": [
        "CWE-1333"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21868.json",
    "cna_assigner": "GitHub_M"
}
References

Affected packages

Git / github.com/flagforgectf/flagforge

Affected ranges

Type
GIT
Repo
https://github.com/flagforgectf/flagforge
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
Database specific
{
    "versions": [
        {
            "introduced": "0"
        },
        {
            "fixed": "2.3.3"
        }
    ]
}

Affected versions

Other
ctf
v2
v2.*
v2.2
v2.3
v2.3.1
v2.3.2

Database specific

source
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-21868.json"