CVE-2026-124551

MEDIUM 5.3

ClassroomIO through 1.0.0 Cross-Organization Course Disclosure via Clone Endpoint

CVSS Score

5.3

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-639
Vendor	classroomio
Product	classroomio
Published	Nov 8, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Attack Vector

Network

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Affected Versions

classroomio / classroomio

0 ≤ 1.0.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/classroomio/classroomio/issues/1414 github.com: https://github.com/classroomio/classroomio github.com: https://github.com/classroomio/classroomio/commit/6630b73f8d53e316de6f575a170b093da6bf3cca hackmd.io: https://hackmd.io/@hieuPenguinnn/classroomio-course-clone-cross-org-content-exfiltration github.com: https://github.com/classroomio/classroomio/blob/v1.0.0/apps/api/src/routes/course/course.ts#L584-L612 github.com: https://github.com/classroomio/classroomio/blob/v1.0.0/apps/api/src/services/course/clone.ts#L202-L290 vulncheck.com: https://www.vulncheck.com/advisories/classroomio-through-1.0.0-cross-organization-course-disclosure-via-clone-endpoint

Credits

hieuPenguinnn Rotimi Best