Auth bypass in Ctfd
CVE-2026-121562
CTFd 3.1.0 before 3.8.7 contains an information disclosure vulnerability in the /api/v1/teams list endpoint that exposes non-public team custom field values. Unauthenticated attackers can paginate GET requests to collect hidden registration data such as emails, phone numbers, and student IDs when team mode and public visibility are enabled.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/CTFd/CTFd/commit/122c224030224ca6a04d2928280055a84bbd4850 (patch)
- github.com/CTFd/CTFd (product)
- github.com/CTFd/CTFd/blob/3.8.6/CTFd/api/v1/teams.py (technical-description)
- github.com/CTFd/CTFd/blob/3.8.6/CTFd/schemas/teams.py (technical-description)
- blog.ctfd.io/ctfd-3-8-7/ (technical-description)
- github.com/CTFd/CTFd/releases/tag/3.8.7 (release-notes, technical-description)
- www.vulncheck.com/advisories/ctfd-3.1.0-before-3.8.7-information-disclosure-via… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-121562?
- CVE-2026-121562 is a medium-severity vulnerability in Ctfd, classified under Incorrect Authorization. CVSS score: 5.3/10. Published 2026-11-03.
- How severe is CVE-2026-121562?
- Medium severity. CVSS v3 base score is 5.3 out of 10.