Moodle 3.10.3 Calendar Event subtitle track label cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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5.5$0-$5k0.00

Summaryinfo

A vulnerability has been found in Moodle 3.10.3 and classified as problematic. Affected by this vulnerability is an unknown functionality of the component Calendar Event Handler. Performing a manipulation of the argument subtitle track label results in cross site scripting. This vulnerability is reported as CVE-2021-47857. The attack is possible to be carried out remotely. Moreover, an exploit is present.

Detailsinfo

A vulnerability was found in Moodle 3.10.3. It has been classified as problematic. This affects an unknown part of the component Calendar Event Handler. The manipulation of the argument subtitle track label with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. The summary by CVE is:

Moodle 3.10.3 contains a persistent cross-site scripting vulnerability in the calendar event subtitle field that allows attackers to inject malicious scripts. Attackers can craft a calendar event with malicious JavaScript in the subtitle track label to execute arbitrary code when users view the event.

The weakness was disclosed by Vincent666 Ibn Winnie as 49714. The advisory is shared at exploit-db.com. This vulnerability is uniquely identified as CVE-2021-47857 since 01/14/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. It demands that the victim is doing some kind of user interaction. Technical details and a public exploit are known. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

The exploit is shared for download at exploit-db.com. It is declared as proof-of-concept.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Exploit-DB (49714). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.6
VulDB Meta Temp Score: 5.5

VulDB Base Score: 3.5
VulDB Temp Score: 3.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 6.1
NVD Vector: 🔒

CNA Base Score: 7.2
CNA Vector (VulnCheck): 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Access: Public
Status: Proof-of-Concept
Download: 🔒

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Exploit-DB: 🔒

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

01/14/2026 CVE reserved
01/21/2026 +7 days Advisory disclosed
01/21/2026 +0 days VulDB entry created
03/05/2026 +43 days VulDB entry last update

Sourcesinfo

Product: moodle.org

Advisory: 49714
Researcher: Vincent666 Ibn Winnie
Status: Not defined

CVE: CVE-2021-47857 (🔒)
GCVE (CVE): GCVE-0-2021-47857
GCVE (VulDB): GCVE-100-342177
scip Labs: https://www.scip.ch/en/?labs.20161013

Entryinfo

Created: 01/21/2026 20:00
Updated: 03/05/2026 21:02
Changes: 01/21/2026 20:00 (81), 03/05/2026 21:02 (11)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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