Cyber Resilience

CVE-2021-3851

MediumPublic PoC

Published: 19 October 2021

Published
19 October 2021
Modified
21 November 2024
KEV Added
—
Patch
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CVSS Score v3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
EPSS Score 0.0017 37.9th percentile
Risk Priority 11 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-3851 is a medium-severity Open Redirect (CWE-601) vulnerability in Firefly-Iii Firefly Iii. Its CVSS base score is 5.4 (Medium).

Operationally, ranked at the 37.9th 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

firefly-iii is vulnerable to URL Redirection to Untrusted Site

CWE(s)
CWE-601

Related Threats

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

Affected Assets

firefly-iii
firefly iii
≤ 5.6.2

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.

AT-2 Literacy Training and Awareness
addresses: CWE-601

Security awareness includes verifying URLs and avoiding untrusted redirects that lead to malicious sites.

SI-10 Information Input Validation
addresses: CWE-601

Validates redirect targets and URLs to ensure they conform to allowed destinations.

References