How severe is CVE-2021-36539?

CVE-2021-36539 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-36539 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-36539?

CVE-2021-36539 affects Instructure Canvas Learning Management Service. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-36539?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-36539 published?

CVE-2021-36539 was published on 2023-01-26 and last updated on 2026-06-17.

CVE-2021-36539

CVE-2021-36539 is a medium-severity vulnerability in Instructure Canvas Learning Management Service with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-639.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-639
Affected product: Instructure Canvas Learning Management Service
Published: 2023-01-26
Last modified: 2026-06-17

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Instructure Canvas LMS didn't properly deny access to locked/unpublished files when the unprivileged user access the DocViewer based file preview URL (canvadoc_session_url).

Frequently asked questions

What is CVE-2021-36539?: Instructure Canvas LMS didn't properly deny access to locked/unpublished files when the unprivileged user access the DocViewer based file preview URL (canvadoc_session_url).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 severe is CVE-2021-36539?: CVE-2021-36539 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-36539 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-36539?: CVE-2021-36539 affects Instructure Canvas Learning Management Service. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-36539?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-36539 published?: CVE-2021-36539 was published on 2023-01-26 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:instructure:canvas_learning_management_service:*:*:*:*:*:*:*:*

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