# CVE-2021-33393: Privilege escalation in n/a

> An attacker with unprivileged access can replace a backup script to execute arbitrary code as root due to insecure file ownership.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Jun 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-6r47-xw28-7649

## What is CVE-2021-33393?

CVE-2021-33393 is a high-severity vulnerability in n/a, published on 9 Jun 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

lfs/backup in IPFire 2.25-core155 does not ensure that /var/ipfire/backup/bin/backup.pl is owned by the root account. It might be owned by an unprivileged account, which could potentially be used to install a Trojan horse backup.pl script that is later executed by root. Similar problems with the ownership/permissions of other files may be present as well.

## Which versions are affected by CVE-2021-33393?

It affects 1 product.


Products: Ipfire Ipfire.

## How do I fix CVE-2021-33393?

No fix has been published for CVE-2021-33393 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-33393 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-33393 exists.

Public exploit code:

- This exploit is based on CVE-2021-33393 and was built upon the original exploit by Mücahit Saratar, extending it to achieve a reverse shell with root privileges. (github_poc): https://github.com/joaoaugustom/IPFire_2.25_RCE_Authenticated
- IPFire 2.25 - Remote Code Execution (Authenticated) (exploitdb)
- IPFire 2.25 Core Update 156 and Prior pakfire.cgi Authenticated RCE (metasploit)

## Other vulnerabilities in n/a

- [CVE-2018-16232](https://insights.sbomify.com/CVE-2018-16232/): Command injection in n/a (high 8.8)
- [CVE-2017-9757](https://insights.sbomify.com/CVE-2017-9757/): Command injection in n/a (high 8.8)
- [CVE-2025-34311](https://insights.sbomify.com/CVE-2025-34311/): IPFire < v2.29 Command Injection via Proxy Report Creation (high 8.7)
- [CVE-2025-34312](https://insights.sbomify.com/CVE-2025-34312/): IPFire < v2.29 Command Injection via URL Filter Blacklist (high 8.7)
- [CVE-2025-34304](https://insights.sbomify.com/CVE-2025-34304/): IPFire < v2.29 SQL Injection via OpenVPN Connection Logs (high 7.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-33393 and fix it if it is affected.

What it is: CVE-2021-33393 is a high-severity vulnerability in n/a, published on 9 Jun 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-33393 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-2021-33393/ (Markdown: https://insights.sbomify.com/CVE-2021-33393/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-33393
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-33393
- OSV: https://osv.dev/vulnerability/CVE-2021-33393

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-33393/
Summaries are generated and may contain mistakes; the official description above is the record.