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Fencer Vulns
medium 6.1

CVE-2021-43558 json

Cross-site Scripting in moodle

published 2021-11-22 4 y ago modified 2026-09-08 2 mo ago also BIT-moodle-2021-43558 , EUVD-2021-2406 , GHSA-wpfp-q843-v772

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

Summary

A flaw was found in Moodle in versions 3.11 to 3.11.3, 3.10 to 3.10.7, 3.9 to 3.9.10 and earlier unsupported versions. A URL parameter in the filetype site administrator tool required extra sanitizing to prevent a reflected XSS risk.

Patch / fix

  • packagist moodle/moodle 3.9.11, 3.10.8, 3.11.4
  • bitnami moodle 3.8.9, 3.9.11, 3.10.8, 3.11.4
  • moodle moodle 3.9.11, 3.10.8, 3.11.4

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-43558 updated

moodle: reflected XSS in filetype admin tool

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.87% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
GitHub 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N
OSV 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
packagist moodle/moodle
>=3.11.0, <3.11.4
>=3.10.0, <3.10.8
>=3.9.0, <3.9.11
3.11.4
3.10.8
3.9.11
bitnami moodle
<3.8.9
>=3.9.0, <3.9.11
>=3.10.0, <3.10.8
>=3.11.0, <3.11.4
3.8.9
3.9.11
3.10.8
3.11.4

Affected products

  • n/a moodle

Classification

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

References

Sources

Fencer Vulns 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.