Cyber Resilience

CVE-2021-3964

MediumPublic PoC

Published: 01 December 2021

Published
01 December 2021
Modified
21 November 2024
KEV Added
—
Patch
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CVSS Score v3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS Score 0.0018 39.2th percentile
Risk Priority 12 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-3964 is a medium-severity Authorization Bypass Through User-Controlled Key (CWE-639) vulnerability in Elgg Elgg. Its CVSS base score is 5.9 (Medium).

Operationally, ranked at the 39.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability details

elgg is vulnerable to Authorization Bypass Through User-Controlled Key

CWE(s)
CWE-639

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

elgg
elgg
≤ 3.3.22

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

AC-24 Access Control Decisions
addresses: CWE-639

Per-request decision making makes it harder to bypass authorization using user-controlled keys without proper validation in the decision process.

AC-3 Access Enforcement
addresses: CWE-639

Consistent enforcement of approved authorizations makes bypassing via user-controlled keys ineffective.

References