CVE-2021-3851

Name: CVE-2021-3851
Creator: NVD / NIST
Published: 2021-10-19T13:15:11.62+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.4/10EPSS 0.55%

Last modified Jun 17, 2026

CVE-2021-3851 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. firefly-iii is vulnerable to URL Redirection to Untrusted Site. EPSS estimates a 0.55% chance of exploitation in the next 30 days.

Description

firefly-iii is vulnerable to URL Redirection to Untrusted Site

Metrics

CVSS 3.1

5.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

0.55%

41.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Firefly-Iii	Firefly Iii	< 5.6.2

References

https://github.com/firefly-iii/firefly-iii/commit/8662dfa4c0f71efef61c31dc015c6f723db8318dPatch, Third Party Advisory
https://huntr.dev/bounties/549a1040-9b5e-420b-9b80-20700dd9d592Exploit, Patch, Third Party Advisory
https://github.com/firefly-iii/firefly-iii/commit/8662dfa4c0f71efef61c31dc015c6f723db8318dPatch, Third Party Advisory
https://huntr.dev/bounties/549a1040-9b5e-420b-9b80-20700dd9d592Exploit, Patch, Third Party Advisory

Timeline

Published: Oct 19, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3851?

firefly-iii is vulnerable to URL Redirection to Untrusted Site

How severe is CVE-2021-3851?

CVE-2021-3851 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.55% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3851?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-3851?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST