CVE-2021-3851

Open Redirect in firefly-iii/firefly-iii

5.0 MediumFix available

firefly-iii is vulnerable to URL Redirection to Untrusted Site

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: Required

What an attacker can affect

Confidentiality: Low
Integrity: Low
Availability: Low

Exploit likelihood

0.57%Down 0.1 points since Oct 20, 2021

What each source reports

CVE List Score used 5.0

Open Redirect in firefly-iii/firefly-iii

firefly-iii is vulnerable to URL Redirection to Untrusted Site

Record: CVE-2021-3851
CVSS 3.0: 5.0 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
Weakness: CWE-601
Updated: 2026-11-02

EUVDEUVD-2021-2160 5.0

firefly-iii is vulnerable to URL Redirection to Untrusted Site

Record: EUVD-2021-2160
CVSS 3.0: 5.0 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
Updated: 2026-11-03

GitHub AdvisoriesGHSA-5fvx-5p2r-4mvp 5.0

Open Redirect in firefly-iii

firefly-iii is vulnerable to URL Redirection to Untrusted Site

Record: GHSA-5fvx-5p2r-4mvp
CVSS 3.0: 5.0 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
Weakness: CWE-601
Updated: 2026-11-02

NVD 5.4

firefly-iii is vulnerable to URL Redirection to Untrusted Site

Record: CVE-2021-3851
CVSS 3.1: 5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CVSS 3.0: 5.0 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
CVSS 2.0: 4.9 MediumAV:N/AC:M/Au:S/C:P/I:P/A:N
Weakness: CWE-601
Updated: 2026-11-02

OSV 5.4

firefly-iii is vulnerable to URL Redirection to Untrusted Site

Record: CVE-2021-3851
CVSS 3.1: 5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Updated: 2026-11-02

OSVGHSA-5fvx-5p2r-4mvp 5.0

Open Redirect in firefly-iii

firefly-iii is vulnerable to URL Redirection to Untrusted Site

Record: GHSA-5fvx-5p2r-4mvp
CVSS 3.0: 5.0 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
Weakness: CWE-601
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`grumpydictator/firefly-iii` Packagist	before 5.6.2	5.6.2
`grumpydictator/firefly-iii` Packagist	before 5.6.2, plus listed versions 3.0.03.0.13.0.23.0.33.1 Show 45 moreShow less 3.1.13.1.23.1.33.1.43.1.53.1.63.103.10.13.10.23.10.33.10.43.2.03.2.13.2.23.2.33.2.43.2.53.33.3.13.3.23.3.33.3.43.3.53.3.63.3.73.3.83.3.93.43.4.0.13.4.0.103.4.0.23.4.0.33.4.0.43.4.0.53.4.0.63.4.0.73.4.0.83.4.0.93.4.13.4.103.4.113.4.23.4.33.4.43.4.4.1	5.6.2

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-3851 is a medium vulnerability (CVSS 5.0) in Firefly-iii Firefly-iii/firefly-iii, published October 19, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.57%, the 47th percentile. Fixed in grumpydictator/firefly-iii 5.6.2.

References

This page doesn't list everything

Left out here: 198 versions. The JSON record has them.