CVE-2021-3964

Authorization Bypass Through User-Controlled Key in elgg/elgg

4.3 MediumFix available

elgg is vulnerable to Authorization Bypass Through User-Controlled Key

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: Low
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: Low
Availability: None

Exploit likelihood

0.80%Up 0.2 points since Dec 2, 2021

What each source reports

CVE List Score used 4.3

Authorization Bypass Through User-Controlled Key in elgg/elgg

elgg is vulnerable to Authorization Bypass Through User-Controlled Key

Record: CVE-2021-3964
CVSS 3.0: 4.3 MediumCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Weakness: CWE-639
Updated: 2026-11-02

EUVDEUVD-2021-2525 4.3

elgg is vulnerable to Authorization Bypass Through User-Controlled Key

Record: EUVD-2021-2525
CVSS 3.0: 4.3 MediumCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Updated: 2026-11-03

GitHub AdvisoriesGHSA-gwpx-q2h9-wxgx 5.9

elgg is vulnerable to Authorization Bypass Through User-Controlled Key

elgg is vulnerable to Authorization Bypass Through User-Controlled Key

Record: GHSA-gwpx-q2h9-wxgx
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness: CWE-639
Updated: 2026-11-02

NVD 5.9

elgg is vulnerable to Authorization Bypass Through User-Controlled Key

Record: CVE-2021-3964
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS 3.0: 4.3 MediumCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
CVSS 2.0: 4.3 MediumAV:N/AC:M/Au:N/C:N/I:P/A:N
Weakness: CWE-639
Updated: 2026-11-02

OSV 5.9

elgg is vulnerable to Authorization Bypass Through User-Controlled Key

Record: CVE-2021-3964
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated: 2026-11-02

OSVGHSA-gwpx-q2h9-wxgx 5.9

elgg is vulnerable to Authorization Bypass Through User-Controlled Key

elgg is vulnerable to Authorization Bypass Through User-Controlled Key

Record: GHSA-gwpx-q2h9-wxgx
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness: CWE-639
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`elgg/elgg` Packagist	before 3.3.22	3.3.22
`elgg/elgg` Packagist	before 3.3.22, plus listed versions 1.10.01.10.0-rc.11.10.11.10.21.10.3 Show 45 moreShow less 1.10.41.10.51.10.61.11.01.11.11.11.21.11.31.11.41.11.51.11.61.12.01.12.11.12.101.12.111.12.121.12.131.12.141.12.151.12.161.12.171.12.181.12.21.12.31.12.41.12.51.12.61.12.71.12.81.12.91.9.01.9.0-rc.11.9.0-rc.21.9.0-rc.31.9.0-rc.41.9.0-rc.51.9.0-rc.61.9.0-rc.71.9.11.9.21.9.31.9.41.9.51.9.61.9.71.9.8	3.3.22

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-2021-3964 is a medium vulnerability (CVSS 4.3) in Elgg, published December 1, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.80%, the 56th percentile. Fixed in elgg/elgg 3.3.22.

References

This page doesn't list everything

Left out here: 89 versions. The JSON record has them.