What’s Vulnerable › Vulnerabilities

CVE-2021-36539

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2023-01-26 · updated 2026-06-17
• Weakness: CWE-639

Description

Instructure Canvas LMS didn't properly deny access to locked/unpublished files when the unprivileged user access the DocViewer based file preview URL (canvadoc_session_url).

Affected products

• Instructure Canvas Learning Management System (LMS): before 2022-10-15 — fixed in 2022-10-15

How to fix

Upgrade to a fixed version: Instructure Canvas Learning Management System (LMS) 2022-10-15. Check the vendor advisory for mitigations.

References

• https://github.com/gaukas/instructure-canvas-file-oracle
• https://github.com/instructure/canvas-lms/issues/1905
• https://github.com/gaukas/instructure-canvas-file-oracle
• https://github.com/instructure/canvas-lms/issues/1905

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