# CVE-2023-36673: Information disclosure in n/a

> An attacker can intercept plaintext traffic and DNS queries by exploiting insecure routing and DNS configuration in the Avira Phantom VPN client.

- **Severity:** High 7.3 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 9 Aug 2023
- **Updated:** 10 Oct 2024
- **Also known as:** GHSA-r43q-w67j-2696

## What is CVE-2023-36673?

CVE-2023-36673 is a high-severity vulnerability in n/a, published on 9 Aug 2023. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

An issue was discovered in Avira Phantom VPN through 2.23.1 for macOS. The VPN client insecurely configures the operating system such that all IP traffic to the VPN server's IP address is sent in plaintext outside the VPN tunnel, even if this traffic is not generated by the VPN client, while simultaneously using plaintext DNS to look up the VPN server's IP address. This allows an adversary to trick the victim into sending traffic to arbitrary IP addresses in plaintext outside the VPN tunnel. NOTE: the tunnelcrack.mathyvanhoef.com website uses this CVE ID to refer more generally to "ServerIP attack, combined with DNS spoofing, that can leak traffic to an arbitrary IP address" rather than to only Avira Phantom VPN.

Weakness: CWE-319 (Cleartext Transmission of Sensitive Information)

## Which versions are affected by CVE-2023-36673?

It affects 1 product.


Products: Avira Phantom Vpn.

## How do I fix CVE-2023-36673?

No fix has been published for CVE-2023-36673 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-36673 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-36673 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-36673 and fix it if it is affected.

What it is: CVE-2023-36673 is a high-severity vulnerability in n/a, published on 9 Aug 2023. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-36673 exists.

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-2023-36673/ (Markdown: https://insights.sbomify.com/CVE-2023-36673/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-36673
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-36673
- OSV: https://osv.dev/vulnerability/CVE-2023-36673

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-36673/
Summaries are generated and may contain mistakes; the official description above is the record.