CVE-2026-21868 is a Regular Expression Denial of Service (ReDoS) vulnerability affecting Flag Forge versions 2.3.2 and below. An unauthenticated attacker can exploit the /api/user/[username] endpoint by providing a specially crafted username containing regex meta-characters, causing excessive CPU consumption in the MongoDB regex engine. This vulnerability has a CVSS score of 7.5 (HIGH), indicating a network-based attack with low complexity that can lead to a complete denial of service. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
>= 2.0, < 2.3.3CPE matchmatch criteria | cpe:2.3:a:flagforge:flagforge:*:*:*:*:*:*:*:* |
CVSS version used by this source: 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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