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Fencer Intel
medium 5.4

CVE-2021-20186 json

Moodle Cross-site Scripting

published 5y ago modified 2mo ago also BIT-moodle-2021-20186 , EUVD-2022-4109 , GHSA-h8m4-h385-qhqv

cvss
5.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 55%
public exploits
0
none known

Summary

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.

Patch / fix

  • packagist moodle/moodle 3.5.16, 3.8.7, 3.9.4, 3.10.1
  • bitnami moodle 3.5.16, 3.8.7, 3.9.4, 3.10.1
  • moodle moodle 3.5.16, 3.8.7, 3.9.4, 3.10.1

Is CVE-2021-20186 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

0.76% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
GitHub 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 2.1 AV:N/AC:H/Au:S/C:P/I:N/A:N
OSV 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
packagist moodle/moodle
>=3.10, <3.10.1
>=3.9, <3.9.4
>=3.8, <3.8.7
>=3.5, <3.5.16
3.10.1
3.9.4
3.8.7
3.5.16
bitnami moodle
<3.5.16
>=3.8.0, <3.8.7
>=3.9.0, <3.9.4
>=3.10.0, <3.10.1
3.5.16
3.8.7
3.9.4
3.10.1

Affected products

  • n/a moodle

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.