CVE-2026-111368

ClassroomIO through 1.0.0 contains an insecure direct object reference vulnerability in the Hono API course submission routes that allows course tutors or admins to modify submissions in other courses. Attackers can supply their own course id with another course's submission UUID to PUT or DELETE handlers to overwrite answers, grades, feedback, and grading status or delete submissions.

• https://github.com/classroomio/classroomio
• https://github.com/classroomio/classroomio/blob/v1.0.0/apps/api/src/routes/course/submission.ts
• https://github.com/classroomio/classroomio/blob/v1.0.0/packages/db/src/queries/submission/submission.ts#L217-L245
• https://github.com/classroomio/classroomio/commit/1844ad9671a0d9c2566d3431d82f34d39016242c

• https://github.com/classroomio/classroomio
• https://github.com/classroomio/classroomio/blob/v1.0.0/apps/api/src/routes/course/submission.ts
• https://github.com/classroomio/classroomio/blob/v1.0.0/packages/db/src/queries/submission/submission.ts#L217-L245
• https://github.com/classroomio/classroomio/commit/1844ad9671a0d9c2566d3431d82f34d39016242c
• https://hackmd.io/@hieuPenguinnn/classroomio-course-resource-id-scoping-idor
• https://www.vulncheck.com/advisories/classroomio-through-1.0.0-idor-via-course-submission-update-grade-and-delete-routes
• https://hackmd.io/@hieuPenguinnn/classroomio-course-resource-id-scoping-idor

• CRITICALCVE-2024-34323
• MEDIUMCVE-2025-71420PoC
• UNSCOREDCVE-2026-100177PoC
• HIGHCVE-2026-100268
• MEDIUMCVE-2026-100272
• HIGHCVE-2026-100514
• HIGHCVE-2026-100517
• MEDIUMCVE-2026-100531PoC

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