CVE-2021-24455

Tutor LMS <= 1.9.1 - Authenticated Stored Cross-Site Scripting

2021-06-28 00:00

Strategic Overview

Status: Patched in 1.9.2
Affected Plugin: Tutor LMS – eLearning and online course solution
Affected Version: <= 1.9.1
CVSS: 5.5Medium
Weakness type: CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE: CVE-2021-24455

View all Tutor LMS – eLearning and online course solution vulnerabilities

At a glance

CVE-2021-24455 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Tutor LMS WordPress plugin, affecting versions <= 1.9.1. It carries a CVSS score of 5.5 (reachable over the network; low attack complexity). Exploitation requires an authenticated account. The issue is fixed in version 1.9.2; sites on affected versions should update now. Disclosed June 2021, reported by Phu Tran.

Vulnerability Overview

The Tutor LMS – eLearning and online course solution WordPress plugin before 1.9.2 did not escape the Summary field of Announcements (when outputting it in an attribute), which can be created by users as low as Tutor Instructor. This lead to a Stored Cross-Site Scripting issue, which is triggered when viewing the Announcements list, and could result in privilege escalation when viewed by an admin.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user.

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Reaching this weakness in Tutor LMS <= 1.9.1 takes any authenticated account. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For Tutor LMS the fix is 1.9.2: builds <= 1.9.1 are affected, anything from 1.9.2 onward is not.

Remediation

Update to version 1.9.2, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Tutor LMS: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Tutor LMS 1.9.2 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-24455 https://www.wordfence.com/threat-intel/vulnerabilities/id/65526517-aec5-454b-94c0-973359d840e1 https://nvd.nist.gov/vuln/detail/CVE-2021-24455

Related records

Same weakness class

CVSS Vector

5.5

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

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredHigh
User InteractionNone
ScopeChanged
ConfidentialityLow
IntegrityLow
AvailabilityNone

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