# CVE-2024-21500: Improper Restriction of Excessive Authentication Attempts in github.com/greenpau/caddy-security

> Attackers can bypass 2FA rate limiting by automating the multistep authentication process, allowing unauthorized access attempts.

- **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 Feb 2024
- **Updated:** 5 Dec 2024
- **Also known as:** GHSA-vfph-hjfv-cpv2, GO-2024-2563

## What is CVE-2024-21500?

CVE-2024-21500 is a medium-severity vulnerability in github.com/greenpau/caddy-security, published on 17 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-307 (Improper Restriction of Excessive Authentication Attempts)

## Which versions are affected by CVE-2024-21500?

3 open source packages ship an affected version, including github.com/greenpau/caddy-security. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/greenpau/caddy-security` | Go | All versions | None |
| `github.com/greenpau/caddy-security` | Go | All versions to 1.1.23 | None |
| `github.com/greenpau/caddy-security` | Go | All versions to 1.1.23 | None |

Products: Authcrunch Caddy-Security.

## How do I fix CVE-2024-21500?

No fix has been published for CVE-2024-21500 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-21500 being exploited?

There is no known exploitation of CVE-2024-21500 in the wild and no public exploit code.

## Other vulnerabilities in github.com/greenpau/caddy-security

- [CVE-2024-21496](https://insights.sbomify.com/CVE-2024-21496/): Cross-site Scripting in github.com/greenpau/caddy-security (medium 6.1)
- [CVE-2023-52430](https://insights.sbomify.com/CVE-2023-52430/): caddy-security plugin for Caddy vulnerable to reflected Cross-site Scripting (medium 5.4)
- [CVE-2024-21498](https://insights.sbomify.com/CVE-2024-21498/): Server-Side Request Forgery in github.com/greenpau/caddy-security (medium 5.3)
- [CVE-2024-21492](https://insights.sbomify.com/CVE-2024-21492/): Insufficient Session Expiration in github.com/greenpau/caddy-security (medium 4.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-21500 and fix it if it is affected.

What it is: CVE-2024-21500 is a medium-severity vulnerability in github.com/greenpau/caddy-security, published on 17 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-21500 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/greenpau/caddy-security (Go): affected all versions; no fix listed
- github.com/greenpau/caddy-security (Go): affected all versions up to 1.1.23; no fix listed
- github.com/greenpau/caddy-security (Go): affected all versions up to 1.1.23; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-21500/ (Markdown: https://insights.sbomify.com/CVE-2024-21500/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-21500
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-21500
- OSV: https://osv.dev/vulnerability/CVE-2024-21500

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-21500/
Summaries are generated and may contain mistakes; the official description above is the record.