CVE-2023-23611: xblock-lti-consumer contain Missing Authorization in Grade Pass Back Implementation
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 resourcelinkid 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 resourcelinkid field of the associated line item. Because the LTI tool could have submitted any value for the resourcelinkid 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 resourcelinkid (i.e. block location) for that XBlock.
The impact is a loss of integrity for LTI XBlock grades.
Patches No available patch
Workarounds No
Other sources
LTI Consumer XBlock implements the consumer side of the LTI specification enabling integration of third-party LTI provider tools. Versions 7.0.0 and above, prior to 7.2.2, are vulnerable to Missing Authorization. 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. 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 resourcelinkid field of the associated line item. The LTI tool may submit any value for the resourcelinkid field, allowing a malicious LTI tool to submit scores for any LTI XBlock on the platform. The impact is a loss of integrity for LTI XBlock grades. This issue is patched in 7.2.2. No workarounds exist.
— NVD
Affected Software
Event History
Frequently Asked Questions
What is CVE-2023-23611?
CVE-2023-23611 is a vulnerability in the LTI Consumer XBlock that allows unauthorized access to third-party LTI provider tools integrated with Open edX.
What is the severity of CVE-2023-23611?
The severity of CVE-2023-23611 is medium with a CVSS score of 5.4.
How does CVE-2023-23611 affect Open edX?
CVE-2023-23611 affects Open edX versions 7.0.0 and above, prior to 7.2.2, by allowing LTI tools to post unauthorized grades.
How can I fix CVE-2023-23611?
To fix CVE-2023-23611, you should upgrade the Open edX platform to version 7.2.2 or above.