LTI 1.3 Grade Pass Back Implementation has Missing Authorization Vulnerability
Problem
TL;DR: Any LTI tool that is integrated with on the Open edX platform can post a grade back for any LTI XBlock so long as it knows or can guess the block location for that XBlock.
In LTI 1.3, LTI tools can "pass back" scores that learners earn while using LTI tools to the edX platform. The edX platform then stores those LTI scores in a separate table. If the right conditions are met, these scores are then persisted to the LMS grades tables.
LTI tools can create what are called "line items" on the edX platform. A line item can be thought of as a column in a grade book; it stores results for a specific activity (i.e. XBlock) for a specific set of users (i.e. users in the course using the XBlock). A line item has an optional resource_link_id field, which is basically the XBlock location. An LTI tool can supply any value for this field.
An LTI tool submits scores to the edX platform for line items. The code that uploads that score to the LMS grade tables determines which XBlock to upload the grades for by reading the resource_link_id field of the associated line item. Because the LTI tool could have submitted any value for the resource_link_id field, this introduces the potential for a nefarious LTI tool to submit scores for any LTI XBlock on the platform.
Impact
Any LTI tool that is integrated with on the Open edX platform can post a grade back for any LTI XBlock so long as it knows the resource_link_id (i.e. block location) for that XBlock.
The impact is a loss of integrity for LTI XBlock grades.
Patches
No available patch
Workarounds
No
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | lti-consumer-xblock | >= 7.0.0, < 7.2.2 | 7.2.2 |
References
- https://github.com/openedx/xblock-lti-consumer/security/advisories/GHSA-7j9p-67mm-5g87
- https://nvd.nist.gov/vuln/detail/CVE-2023-23611
- https://github.com/openedx/xblock-lti-consumer/commit/252f94bd182cd0962af9251015930cb55ec515d7
- https://github.com/openedx/xblock-lti-consumer
- https://github.com/pypa/advisory-database/tree/main/vulns/lti-consumer-xblock/PYSEC-2023-21.yaml
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N- Weakness (CWE)
CWE-862- Platform
- Python (PyPI)
- Package
lti-consumer-xblock- Disclosed
- 26.01.2023
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2023-21 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-7j9p-67mm-5g87 - CC BY 4.0
Vulnerability history: lti-consumer-xblock
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.