Auth bypass in Classroomio
CVE-2026-124551
ClassroomIO through 1.0.0 contains an authorization bypass vulnerability that allows authenticated users of any organization to clone other tenants' courses via the POST /course/:courseId/clone endpoint. Attackers who know a target course id can copy its sections, lessons, exercises, and quiz answer keys into their own organization, exposing private course content.
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/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/classroomio/classroomio (product)
- github.com/classroomio/classroomio/blob/v1.0.0/apps/api/src/routes/course/cours… (technical-description)
- github.com/classroomio/classroomio/blob/v1.0.0/apps/api/src/services/course/clo… (technical-description)
- github.com/classroomio/classroomio/commit/6630b73f8d53e316de6f575a170b093da6bf3… (patch)
- github.com/classroomio/classroomio/issues/1414 (issue-tracking)
- hackmd.io/@hieuPenguinnn/classroomio-course-clone-cross-org-content-exfiltration (technical-description)
- www.vulncheck.com/advisories/classroomio-through-1.0.0-cross-organization-cours… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-124551?
- CVE-2026-124551 is a medium-severity vulnerability in Classroomio, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 5.3/10. Published 2026-11-08.
- How severe is CVE-2026-124551?
- Medium severity. CVSS v3 base score is 5.3 out of 10.