What is CVE-2021-3846?

CVE-2021-3846 is a high-severity vulnerability in Firefly-Iii Firefly Iii, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 8.8/10. Published 2021-10-19.

How severe is CVE-2021-3846?

High severity. CVSS v3 base score is 8.8 out of 10.

Arbitrary file upload in Firefly-Iii Firefly Iii

CVE-2021-3846

firefly-iii is vulnerable to Unrestricted Upload of File with Dangerous Type

Vulnerability class: Unrestricted File Upload

Published 2021-10-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.008 (54.2th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 54.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Firefly-Iii Firefly Iii
Firefly-Iii Firefly-Iii/firefly-Iii — versions unspecified

Weakness classification (CWE)

CWE-434 — Unrestricted Upload of File with Dangerous Type

References

huntr.dev/bounties/5267ec1c-d204-40d2-bd4f-6c2dd495ee18 (Exploit, Patch, Third Party Advisory)
github.com/firefly-iii/firefly-iii/commit/a85b6420c19ace35134f896e094e1971d8c79… (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-3846?: CVE-2021-3846 is a high-severity vulnerability in Firefly-Iii Firefly Iii, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 8.8/10. Published 2021-10-19.
How severe is CVE-2021-3846?: High severity. CVSS v3 base score is 8.8 out of 10.