# CVE-2021-29418: Security feature bypass in n/a

> Attackers can bypass IP-based access controls by exploiting improper input validation in the netmask Node.js library.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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:** Yes
- **Published:** 30 Mar 2021
- **Updated:** 3 Aug 2024

## What is CVE-2021-29418?

CVE-2021-29418 is a medium-severity vulnerability in n/a, published on 30 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The netmask package before 2.0.1 for Node.js mishandles certain unexpected characters in an IP address string, such as an octal digit of 9. This (in some situations) allows attackers to bypass access control that is based on IP addresses. NOTE: this issue exists because of an incomplete fix for CVE-2021-28918.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-29418?

It affects 1 product.


Products: Netmask Project Netmask.

## How do I fix CVE-2021-29418?

Upgrade to a fixed version.

## Is CVE-2021-29418 being exploited?

There is no known exploitation of CVE-2021-29418 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-28918](https://insights.sbomify.com/CVE-2021-28918/): Server-side request forgery in n/a (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-29418 and fix it if it is affected.

What it is: CVE-2021-29418 is a medium-severity vulnerability in n/a, published on 30 Mar 2021. 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-2021-29418 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2021-29418/ (Markdown: https://insights.sbomify.com/CVE-2021-29418/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-29418
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-29418
- OSV: https://osv.dev/vulnerability/CVE-2021-29418

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-29418/
Summaries are generated and may contain mistakes; the official description above is the record.