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Vulnerability record · CVE-2021-36539 · published 26 January 2023

CVE-2021-36539: Instructure canvas learning management service insecure direct object reference vulnerability

Instructure · Canvas Learning Management Service

Instructure Canvas LMS didn't properly deny access to locked/unpublished files when the unprivileged user access the DocViewer based file preview URL (canvadoc_session_url).

6.5 CVSS 3.1 Medium EPSS 0.87% · top 42.7% CWE-639 · Insecure direct object reference
6.5CVSS 3.1 base score
0.87%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 4 tagged exploit
17 Jun 2026Last modified by NVD

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Instructure Canvas LMS didn't properly deny access to locked/unpublished files when the unprivileged user access the DocViewer based file preview URL (canvadoc_session_url).

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/gaukas/instructure-canvas-file-oracle ExploitThird Party Advisory
https://github.com/instructure/canvas-lms/issues/1905 ExploitThird Party Advisory
https://github.com/gaukas/instructure-canvas-file-oracle ExploitThird Party Advisory
https://github.com/instructure/canvas-lms/issues/1905 ExploitThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

5.8CVE-2020-5775Instructure canvas learning management service server-side request forgery (ssrf) vulnerabilityServer-Side Request Forgery in Canvas LMS 2020-07-29 allows a remote, unauthenticated attacker to cause the Canvas application to perform HTTP GET re…EPSS 6.5%8.4CVE-2026-55255Langflow IDOR in responses endpoint allows cross-user flow executionLangflow before 1.9.1 has an insecure direct object reference in the /api/v1/responses endpoint. An authenticated attacker can supply another user's …KEVEPSS 0.89%analysed

Source: NIST National Vulnerability Database (record CVE-2021-36539), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.