What is CVE-2021-3819?

CVE-2021-3819 is a high-severity vulnerability in Firefly-Iii Firefly Iii, classified under Cross-Site Request Forgery (CSRF). CVSS score: 8.8/10. Published 2021-09-27.

How severe is CVE-2021-3819?

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

CSRF in Firefly-Iii Firefly Iii

CVE-2021-3819

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

Vulnerability class: CSRF (Cross-Site Request Forgery)

Published 2021-09-27 · last modified 2026-06-17.

CVSS v3 metric

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

EPSS exploit prediction

EPSS: 0.005 (43.2th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 43.2% 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/da82f7b6-4ffc-4109-87a4-a2a790bd44e5 (Exploit, Patch, Third Party Advisory)
github.com/firefly-iii/firefly-iii/commit/578f350498b75f31d321c78a608c7f7b3b7b0… (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-3819?: CVE-2021-3819 is a high-severity vulnerability in Firefly-Iii Firefly Iii, classified under Cross-Site Request Forgery (CSRF). CVSS score: 8.8/10. Published 2021-09-27.
How severe is CVE-2021-3819?: High severity. CVSS v3 base score is 8.8 out of 10.