# CVE-2018-3759: private_address_check contains race condition

> A race condition in the private_address_check Ruby gem allows attackers to bypass SSRF protections by exploiting DNS TTL changes.

- **Severity:** Low 3.7 (`CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/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:** 13 Jun 2018
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-2xvj-j3qh-x8c3

## What is CVE-2018-3759?

CVE-2018-3759 is a low-severity vulnerability in HackerOne private_address_check ruby gem, published on 13 Jun 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

private_address_check ruby gem before 0.5.0 is vulnerable to a time-of-check time-of-use (TOCTOU) race condition due to the address the socket uses not being checked. DNS entries with a TTL of 0 can trigger this case where the initial resolution is a public address but the subsequent resolution is a private address.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2018-3759?

2 open source packages ship an affected version, including private_address_check. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `private_address_check` | RubyGems | All versions | 0.5.0 |
| `private_address_check` | RubyGems | All versions | 0.5.0 |

Products: Private Address Check Project Private Address Check.

## How do I fix CVE-2018-3759?

Upgrade private_address_check to 0.5.0 or later.

## Is CVE-2018-3759 being exploited?

There is no known exploitation of CVE-2018-3759 in the wild and no public exploit code.

## Other vulnerabilities in HackerOne private_address_check ruby gem

- [CVE-2017-0909](https://insights.sbomify.com/CVE-2017-0909/): private_address_check contains Incomplete List of Disallowed Inputs (critical 9.8)
- [CVE-2017-0904](https://insights.sbomify.com/CVE-2017-0904/): private_address_check vulnerable to bypass of Resolv.getaddresses method (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-3759 and fix it if it is affected.

What it is: CVE-2018-3759 is a low-severity vulnerability in HackerOne private_address_check ruby gem, published on 13 Jun 2018. 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-2018-3759 in the wild and no public exploit code.

Affected packages and fixed versions:
- private_address_check (RubyGems): affected all versions; fixed in 0.5.0
- private_address_check (RubyGems): affected all versions; fixed in 0.5.0

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-2018-3759/ (Markdown: https://insights.sbomify.com/CVE-2018-3759/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-3759
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-3759
- OSV: https://osv.dev/vulnerability/CVE-2018-3759

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-3759/
Summaries are generated and may contain mistakes; the official description above is the record.