CVE-2021-24455Public exploitNetwork attack vector

Privilege escalation via unescaped announcement summary

Published Aug 2, 2021 · Updated Aug 3, 2024

Stored XSS in Themeum Tutor LMS before 1.9.2 allows remote authenticated users to run script in an administrator's browser. The Announcements list places the stored Summary field inside an HTML attribute without escaping, allowing crafted attribute content to install an event handler. Tutor Instructor access is sufficient to create the announcement, but an administrator must view the list; script runs in the site's origin and can perform administrator actions.

CVSS severity5.4
Medium
EPSS probability0.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Themeum Tutor LMS before 1.9.2 allows remote authenticated users to run script in an administrator's browser. The Announcements list places the stored Summary field inside an HTML attribute without escaping, allowing crafted attribute content to install an event handler. Tutor Instructor access is sufficient to create the announcement, but an administrator must view the list; script runs in the site's origin and can perform administrator actions.

The record

CVE
CVE-2021-24455
Published
Aug 2, 2021
Updated
Aug 3, 2024
Vendor
Themeum
Product
Tutor LMS
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 2, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.9.2 <1.9.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Themeum · Tutor LMSversion=1.9.2 <1.9.2

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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