CVE-2021-20186
Moodle Cross-site Scripting
It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that if the TeX notation filter was enabled, additional sanitizing of TeX content was required to prevent the risk of stored XSS.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that if the TeX notation filter was enabled, additional sanitizing of TeX content was required to prevent the risk of stored XSS.
- Record
CVE-2021-20186- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - CVSS 2.0
- 2.1 Low
AV:N/AC:H/Au:S/C:P/I:N/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
CVE List No score
It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that if the TeX notation filter was enabled, additional sanitizing of TeX content was required to prevent the risk of stored XSS.
- Record
CVE-2021-20186- Weakness
- CWE-79
- Updated
- 2026-11-02
EUVDEUVD-2022-4109 No score
It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that if the TeX notation filter was enabled, additional sanitizing of TeX content was required to prevent the risk of stored XSS.
- Record
EUVD-2022-4109- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-h8m4-h385-qhqv
Moodle Cross-site Scripting
It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that if the TeX notation filter was enabled, additional sanitizing of TeX content was required to prevent the risk of stored XSS.
- Record
GHSA-h8m4-h385-qhqv- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSV
It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that if the TeX notation filter was enabled, additional sanitizing of TeX content was required to prevent the risk of stored XSS.
- Record
CVE-2021-20186- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-02
OSVGHSA-h8m4-h385-qhqv
Moodle Cross-site Scripting
It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that if the TeX notation filter was enabled, additional sanitizing of TeX content was required to prevent the risk of stored XSS.
- Record
GHSA-h8m4-h385-qhqv- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSVUBUNTU-CVE-2021-20186
It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that if the TeX notation filter was enabled, additional sanitizing of TeX content was required to prevent the risk of stored XSS.
- Record
UBUNTU-CVE-2021-20186- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-02
OSVBIT-moodle-2021-20186 No score
It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that if the TeX notation filter was enabled, additional sanitizing of TeX content was required to prevent the risk of stored XSS.
- Record
BIT-moodle-2021-20186- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
moodle/moodlePackagist |
3.10 up to 3.10.1 | 3.10.1 |
moodle/moodlePackagist |
3.9 up to 3.9.4 | 3.9.4 |
moodle/moodlePackagist |
3.8 up to 3.8.7 | 3.8.7 |
moodle/moodlePackagist |
3.5 up to 3.5.16 | 3.5.16 |
moodleBitnami |
before 3.5.16, 3.8.0 up to 3.8.7, 3.9.0 up to 3.9.4, 3.10.0 up to 3.10.1 | 3.5.163.8.73.9.43.10.1 |
moodle/moodlePackagist |
3.10 up to 3.10.1, plus listed versions v3.10.0v3.10.0-betav3.10.0-rc1v3.10.0-rc2 |
3.10.1 |
moodle/moodlePackagist |
3.9 up to 3.9.4, plus listed versions v3.9.0v3.9.0-betav3.9.0-rc1v3.9.0-rc2v3.9.0-rc3v3.9.1v3.9.2v3.9.3 |
3.9.4 |
moodle/moodlePackagist |
3.8 up to 3.8.7, plus listed versions v3.8.0v3.8.0-betav3.8.0-rc1v3.8.1v3.8.2 Show 4 moreShow lessv3.8.3v3.8.4v3.8.5v3.8.6 |
3.8.7 |
moodle/moodlePackagist |
3.5 up to 3.5.16, plus listed versions v3.5.0v3.5.0-betav3.5.0-rc1v3.5.1v3.5.10 Show 13 moreShow lessv3.5.11v3.5.12v3.5.13v3.5.14v3.5.15v3.5.2v3.5.3v3.5.4v3.5.5v3.5.6v3.5.7v3.5.8v3.5.9 |
3.5.16 |
moodleUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 2.7.9+dfsg-12.7.10+dfsg-12.7.11+dfsg-12.7.11+dfsg-22.7.12+dfsg-13.0.3+dfsg-0ubuntu13.0.3+dfsg-0ubuntu1+esm1 |
None known |
moodleUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 3.0.3+dfsg-0ubuntu13.0.3+dfsg-0ubuntu1+esm1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| facts | ||
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-20186 is a medium vulnerability (CVSS 5.4) in Moodle, published January 28, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.76%, the 55th percentile. Fixed in moodle/moodle 3.10.1.