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Fencer Vulns
medium 5.4

CVE-2021-20280 json

Cross-site scripting (XSS) and Server side request forgery (SSRF) in moodle

published 2021-03-15 5 y ago modified 2026-09-08 2 mo ago also BIT-moodle-2021-20280 , EUVD-2021-0721 , GHSA-x2jp-hh65-4xvf

cvss
5.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 70%
public exploits
0
none known

Summary

Text-based feedback answers required additional sanitizing to prevent stored XSS and blind SSRF risks in moodle before 3.10.2, 3.9.5, 3.8.8, 3.5.17.

Patch / fix

  • packagist moodle/moodle 3.5.17, 3.8.8, 3.9.5, 3.10.2
  • bitnami moodle 3.5.17, 3.8.8, 3.9.5, 3.10.2
  • moodle moodle 3.5.17, 3.8.8, 3.9.5, 3.10.2

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-2021-20280 updated

moodle: Stored XSS and blind SSRF possible via feedback answer text

  • 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

1.27% chance of exploitation in the next 30 days, higher than 70% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • packetstormsecurity.com http://packetstormsecurity.com/files/164817/Moodle-Cross-Site-Scripting-Server-Side-Request-Forgery.html referenced PoC, tagged "exploit" by a source, unverified

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 3.5 AV:N/AC:M/Au:S/C:N/I:P/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, <3.10.2
>=3.9, <3.9.5
>=3.8, <3.8.8
>=3.5, <3.5.17
3.10.2
3.9.5
3.8.8
3.5.17
bitnami moodle
>=3.5.0, <3.5.17
>=3.8.0, <3.8.8
>=3.9.0, <3.9.5
>=3.10.0, <3.10.2
3.5.17
3.8.8
3.9.5
3.10.2

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.