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Fencer Vulns
medium 6.1

CVE-2023-23921 json

Moodle: reflected xss risk in some returnurl parameters

published 2023-02-17 3 y ago modified 2026-09-08 2 mo ago also BIT-moodle-2023-23921 , EUVD-2023-0673 , GHSA-97qf-pq7x-964m

cvss
6.1
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 57%
public exploits
0
none known

Summary

The vulnerability was found Moodle which exists due to insufficient sanitization of user-supplied data in some returnurl parameters. A remote attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in user's browser in context of vulnerable website. This flaw allows a remote attacker to perform cross-site scripting (XSS) attacks.

Patch / fix

  • packagist moodle/moodle 3.9.19, 3.11.12, 4.0.6, 4.1.1
  • bitnami moodle 3.9.19, 3.11.12, 4.0.6, 4.1.1
  • moodle moodle 3.9.19, 3.11.12, 4.0.6

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-2023-23921 updated

moodle: Reflected XSS risk in some returnurl parameters

  • 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

0.81% chance of exploitation in the next 30 days, higher than 57% 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
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
<3.9.19
>=3.10.0, <3.11.12
>=4.0.0-beta, <4.0.6
>=4.1.0-beta, <4.1.1
3.9.19
3.11.12
4.0.6
4.1.1
bitnami moodle
>=3.9.0, <3.9.19
>=3.11.0, <3.11.12
>=4.0.0, <4.0.6
>=4.1.0, <4.1.1
3.9.19
3.11.12
4.0.6
4.1.1

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.