What is CVE-2021-3730?

CVE-2021-3730 is a medium-severity vulnerability in Firefly-Iii Firefly Iii, classified under Cross-Site Request Forgery (CSRF). CVSS score: 6.5/10. Published 2021-08-23.

How severe is CVE-2021-3730?

Medium severity. CVSS v3 base score is 6.5 out of 10.

CSRF in Firefly-Iii Firefly Iii

CVE-2021-3730

firefly-iii is vulnerable to Cross-Site Request Forgery (CSRF)

Vulnerability class: CSRF (Cross-Site Request Forgery)

Published 2021-08-23 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.005 (38.6th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 38.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

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

Weakness classification (CWE)

CWE-352 — Cross-Site Request Forgery (CSRF)

References

huntr.dev/bounties/ea181323-51f8-46a2-a60f-6a401907feb7 (Third Party Advisory)
github.com/firefly-iii/firefly-iii/commit/f80178b1b2b7864d17500a131d570c353c9a2… (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-3730?: CVE-2021-3730 is a medium-severity vulnerability in Firefly-Iii Firefly Iii, classified under Cross-Site Request Forgery (CSRF). CVSS score: 6.5/10. Published 2021-08-23.
How severe is CVE-2021-3730?: Medium severity. CVSS v3 base score is 6.5 out of 10.