CVE-2021-36539: Instructure Canvas LMS didn't properly deny access to locked/unpublished files when the unprivileged user acce

Q: How do I fix CVE-2021-36539?

canvas learning management service: upgrade to 2022-10-15. Exact commands for each OS are on this page.

Q: Is CVE-2021-36539 being exploited?

CVE-2021-36539 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-36539 affect?

CVE-2021-36539 affects canvas learning management service. Severity is medium (CVSS 6.5). Instructure Canvas LMS didn't properly deny access to locked/unpublished files when the unprivileged user access the DocViewer based file preview URL (canvadoc_session_url).

Q: How urgent is CVE-2021-36539?

Priority 42/100. Public exploit reference

This month

MEDIUM 6.5UPGRADE

CVE-2021-36539 is a medium-severity flaw (CVSS 6.5) affecting canvas learning management service. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Instructure Canvas LMS didn't properly deny access to locked/unpublished files when the unprivileged user access the DocViewer based file preview URL (canvadoc_session_url).

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.9% (top 41%)
CISA exploited list	No
Weakness	CWE-639
Published	2023-01-26
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: instructure

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-01-26 21:15 UTCPublished CVE record published
2026-06-17 03:58 UTCUpdated Record last modified

instructure canvas learning management service UPGRADE

Affected: < 2022-10-15

Fixed in: 2022-10-15

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy canvas-learning-management-service || rpm -q canvas-learning-management-service || canvas-learning-management-service --version

2. UPGRADE to 2022-10-15 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade canvas-learning-management-service

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade canvas-learning-management-service

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-36539?

canvas learning management service: upgrade to 2022-10-15. Exact commands for each OS are on this page.

Is CVE-2021-36539 being exploited?

CVE-2021-36539 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-36539 affect?

CVE-2021-36539 affects canvas learning management service. Severity is medium (CVSS 6.5). 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).

How urgent is CVE-2021-36539?

Priority 42/100. Public exploit reference

References

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