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CVE-2021-3663

24
FAUCET Score

CVE-2021-3663 describes an Improper Restriction of Excessive Authentication Attempts vulnerability (CWE-307) affecting Firefly III, a personal finance manager. This high-severity vulnerability (CVSS 7.5) allows an unauthenticated attacker to achieve high confidentiality impact through a low-complexity network attack, likely by brute-forcing credentials. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
<= 5.5.12CPE matchmatch criteria
cpe:2.3:a:firefly-iii:firefly_iii:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

5.3MEDIUM

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
LOW
Exploitability Score
1.8
Impact Score
3.4
CvssVersion
3.0

Exploit Intelligence

EPSS Score
0.71%
Probability of exploitation in next 30 days
EPSS Percentile
49.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
This CVE's current EPSS score of 0.0071 is in the 26th percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 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: 5.5.13
github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

composerGHSA-56cx-wf47-hx7wmedium

No Restriction of Excessive Authentication Attempts in Firefly III

Aug 9, 2021

References

github.com / firefly-iii/firefly-iii/commit/afc9f4b7ebc8a240c85864a6e1abda62bfeefae8
PatchThird Party Advisory
huntr.dev / bounties/497bdf6d-7dba-49c3-8011-1c64dfbb3380
ExploitThird Party Advisory