CVE-2021-20280

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

5.4 MediumFix available

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.

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

1.27%Unchanged since Apr 14, 2021

What each source reports

NVD Score used 5.4

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.

Record: CVE-2021-20280
CVSS 3.1: 5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CVSS 2.0: 3.5 LowAV:N/AC:M/Au:S/C:N/I:P/A:N
Weakness: CWE-79
Updated: 2026-11-02

CVE List No score

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.

Record: CVE-2021-20280
Weakness: CWE-79
Updated: 2026-11-02

EUVDEUVD-2021-0721 No score

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.

Record: EUVD-2021-0721
Updated: 2026-11-03

GitHub AdvisoriesGHSA-x2jp-hh65-4xvf 5.4

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

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.

Record: GHSA-x2jp-hh65-4xvf
CVSS 3.1: 5.4 MediumCVSS: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 5.4

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.

Record: CVE-2021-20280
CVSS 3.1: 5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Updated: 2026-11-02

OSVGHSA-x2jp-hh65-4xvf 5.4

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

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.

Record: GHSA-x2jp-hh65-4xvf
CVSS 3.1: 5.4 MediumCVSS: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-2021-20280 5.4

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.

Record: UBUNTU-CVE-2021-20280
CVSS 3.1: 5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Updated: 2026-11-02

OSVBIT-moodle-2021-20280 No score

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.

Record: BIT-moodle-2021-20280
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`moodle/moodle` Packagist	3.10 up to 3.10.2	3.10.2
`moodle/moodle` Packagist	3.9 up to 3.9.5	3.9.5
`moodle/moodle` Packagist	3.8 up to 3.8.8	3.8.8
`moodle/moodle` Packagist	3.5 up to 3.5.17	3.5.17
`moodle` Bitnami	3.5.0 up to 3.5.17, 3.8.0 up to 3.8.8, 3.9.0 up to 3.9.5, 3.10.0 up to 3.10.2	3.5.173.8.83.9.53.10.2
`moodle/moodle` Packagist	3.10 up to 3.10.2, plus listed versions v3.10.0v3.10.0-betav3.10.0-rc1v3.10.0-rc2v3.10.1	3.10.2
`moodle/moodle` Packagist	3.9 up to 3.9.5, plus listed versions v3.9.0v3.9.0-betav3.9.0-rc1v3.9.0-rc2v3.9.0-rc3 Show 4 moreShow less v3.9.1v3.9.2v3.9.3v3.9.4	3.9.5
`moodle/moodle` Packagist	3.8 up to 3.8.8, plus listed versions v3.8.0v3.8.0-betav3.8.0-rc1v3.8.1v3.8.2 Show 5 moreShow less v3.8.3v3.8.4v3.8.5v3.8.6v3.8.7	3.8.8
`moodle/moodle` Packagist	3.5 up to 3.5.17, plus listed versions v3.5.0v3.5.0-betav3.5.0-rc1v3.5.1v3.5.10 Show 14 moreShow less v3.5.11v3.5.12v3.5.13v3.5.14v3.5.15v3.5.16v3.5.2v3.5.3v3.5.4v3.5.5v3.5.6v3.5.7v3.5.8v3.5.9	3.5.17
`moodle` Ubuntu: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
`moodle` Ubuntu:Pro:18.04:LTS	All versions, plus listed versions 3.0.3+dfsg-0ubuntu13.0.3+dfsg-0ubuntu1+esm1	None known

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-20280 is a medium vulnerability (CVSS 5.4) in Moodle, published March 15, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.27%, the 69th percentile. Fixed in moodle/moodle 3.10.2.

References

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