# CVE-2021-3907: Arbitrary filepath traversal via URI injection

> Attackers can write files outside the cache directory via URI injection, potentially leading to remote code execution on the host.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Nov 2021
- **Updated:** 17 Sep 2024
- **Also known as:** DEBIAN-CVE-2021-3907, GHSA-8459-6rc9-8vf8, GHSA-cqh2-vc2f-q4fh, GO-2022-0248, UBUNTU-CVE-2021-3907

## What is CVE-2021-3907?

CVE-2021-3907 is a high-severity path traversal vulnerability in Debian Debian Linux, published on 11 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

OctoRPKI does not escape a URI with a filename containing "..", this allows a repository to create a file, (ex. rsync://example.org/repo/../../etc/cron.daily/evil.roa), which would then be written to disk outside the base cache folder. This could allow for remote code execution on the host machine OctoRPKI is running on.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-3907?

5 open source packages ship an affected version, including github.com/cloudflare/cfrpki. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/cloudflare/cfrpki` | Go | All versions | 1.4.3 |
| `github.com/cloudflare/cfrpki` | Go | All versions | 1.4.3 |
| `github.com/cloudflare/cfrpki` | Go | All versions | 1.4.4 |
| `github.com/cloudflare/cfrpki` | Go | All versions | 1.4.4 |
| `github.com/cloudflare/cfrpki` | Go | All versions | 1.4.4 |

Products: Cloudflare Octorpki, Debian Debian Linux.

## How do I fix CVE-2021-3907?

Upgrade github.com/cloudflare/cfrpki to a fixed version for your release line: 1.4.3 or 1.4.4.

## Is CVE-2021-3907 being exploited?

There is no known exploitation of CVE-2021-3907 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2021-3978](https://insights.sbomify.com/CVE-2021-3978/): Improper Preservation of Permissions in github.com/cloudflare/cfrpki/cmd/octorpki (high 7.5)
- [CVE-2021-3761](https://insights.sbomify.com/CVE-2021-3761/): OctoRPKI lacks contextual out-of-bounds check when validating RPKI ROA maxLength values (high 7.5)
- [CVE-2021-3908](https://insights.sbomify.com/CVE-2021-3908/): Infinite certificate chain depth results in OctoRPKI running forever (medium 5.9)
- [CVE-2022-3616](https://insights.sbomify.com/CVE-2022-3616/): OctoRPKI crash when maximum iterations number is reached (medium 5.4)
- [CVE-2021-3909](https://insights.sbomify.com/CVE-2021-3909/): Infinite open connection causes OctoRPKI to hang forever (medium 4.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3907 and fix it if it is affected.

What it is: CVE-2021-3907 is a high-severity path traversal vulnerability in Debian Debian Linux, published on 11 Nov 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-2021-3907 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/cloudflare/cfrpki (Go): affected all versions; fixed in 1.4.3
- github.com/cloudflare/cfrpki (Go): affected all versions; fixed in 1.4.3
- github.com/cloudflare/cfrpki (Go): affected all versions; fixed in 1.4.4
- github.com/cloudflare/cfrpki (Go): affected all versions; fixed in 1.4.4
- github.com/cloudflare/cfrpki (Go): affected all versions; fixed in 1.4.4

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-2021-3907/ (Markdown: https://insights.sbomify.com/CVE-2021-3907/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3907
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3907
- OSV: https://osv.dev/vulnerability/CVE-2021-3907

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-3907/
Summaries are generated and may contain mistakes; the official description above is the record.