Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2021-3851

20
FAUCET Score

CVE-2021-3851 describes a URL Redirection to Untrusted Site vulnerability affecting Firefly III, a personal finance manager. This medium-severity flaw (CVSS 5.4) allows an attacker to redirect authenticated users to malicious external sites through crafted links, potentially leading to credential theft or phishing. While no public exploits, Metasploit modules, or active exploitation have been observed, and community discussion is minimal, users should remain vigilant for social engineering attempts.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.6.2CPE matchmatch criteria
cpe:2.3:a:firefly-iii:firefly_iii:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

5.0MEDIUM

CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
LOW
Exploitability Score
1.6
Impact Score
3.4
CvssVersion
3.0

Exploit Intelligence

EPSS Score
0.55%
Probability of exploitation in next 30 days
EPSS Percentile
42.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0055 is in the 68th percentile among its peer group of 15,239 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

composerpatch availablevia ghsa
Product: grumpydictator/firefly-iiiFixed in: 5.6.2
github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

composerGHSA-5fvx-5p2r-4mvpmedium

Open Redirect in firefly-iii

Oct 21, 2021

References

github.com / firefly-iii/firefly-iii/commit/8662dfa4c0f71efef61c31dc015c6f723db8318d
PatchThird Party Advisory
huntr.dev / bounties/549a1040-9b5e-420b-9b80-20700dd9d592
ExploitPatchThird Party Advisory