Improper Restriction of Excessive Authentication Attempts in github.com/greenpau/caddy-security

published 2024-02-17 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-0731 , GHSA-vfph-hjfv-cpv2 , GO-2024-2563

cvss: 4.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 45%
public exploits: 0; none known

All versions of the package github.com/greenpau/caddy-security are vulnerable to Improper Restriction of Excessive Authentication Attempts via the two-factor authentication (2FA). Although the application blocks the user after several failed attempts to provide 2FA codes, attackers can bypass this blocking mechanism by automating the application’s full multistep 2FA process.

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 y ago (2024-08-21)

Exploit prediction

0.53% chance of exploitation in the next 30 days, higher than 45% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

blog.trailofbits.com https://blog.trailofbits.com/2023/09/18/security-flaws-in-an-sso-plugin-for-caddy/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.8	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
GitHub	3.1	4.8	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
NVD	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
go	github.com/greenpau/caddy-security	<=1.1.23 all versions	no fix listed

Affected products

n/a github.com/greenpau/caddy-security

Classification

Weakness

CWE-307 Improper Restriction of Excessive Authentication Attempts

References

blog.trailofbits.com /2023/09/18/security-flaws-in-an-sso-plugin-for-caddy/
exploit, third-party-advisory
security.snyk.io /vuln/SNYK-GOLANG-GITHUBCOMGREENPAUCADDYSECURITY-6249864
web, third-party-advisory
github.com /greenpau/caddy-security/issues/271
web, issue-tracking, report
nvd.nist.gov /vuln/detail/CVE-2024-21500
advisory
blog.trailofbits.com /2023/09/18/security-flaws-in-an-sso-plugin-for-caddy
web
github.com /advisories/GHSA-vfph-hjfv-cpv2
advisory

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary