# CVE-2021-31566: Path traversal in libarchive

> A local attacker can exploit improper link resolution in libarchive to modify file permissions and gain privileges by tricking a user into extracting a malicious archive.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **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:** Yes
- **Published:** 23 Aug 2022
- **Updated:** 3 Aug 2024
- **Also known as:** ALPINE-CVE-2021-31566, CLSA-2026-1777307149, CLSA-2026-1777544831, DEBIAN-CVE-2021-31566, GHSA-mg62-fpgc-6hjj, JLSEC-2025-236, SUSE-SU-2022:3935-1, SUSE-SU-2022:3936-1, UBUNTU-CVE-2021-31566

## What is CVE-2021-31566?

CVE-2021-31566 is a high-severity path traversal vulnerability in Debian Debian Linux, published on 23 Aug 2022. 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 improper link resolution flaw can occur while extracting an archive leading to changing modes, times, access control lists, and flags of a file outside of the archive. An attacker may provide a malicious archive to a victim user, who would trigger this flaw when trying to extract the archive. A local attacker may use this flaw to gain more privileges in a system.

Weakness: CWE-59 (Improper Link Resolution Before File Access)

## Which versions are affected by CVE-2021-31566?

It affects 14 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libarchive` | SUSE:Linux Enterprise Micro 5.3 | All versions | 3.5.1-150400.3.9.1 |
| `libarchive` | SUSE:Linux Enterprise Module for Basesystem 15 SP3 | All versions | 3.4.2-150200.4.12.1 |
| `libarchive` | SUSE:Linux Enterprise Module for Basesystem 15 SP4 | All versions | 3.5.1-150400.3.9.1 |
| `libarchive` | SUSE:Linux Enterprise Module for Development Tools 15 SP3 | All versions | 3.4.2-150200.4.12.1 |
| `libarchive` | SUSE:Linux Enterprise Module for Development Tools 15 SP4 | All versions | 3.5.1-150400.3.9.1 |
| `libarchive` | openSUSE:Leap 15.3 | All versions | 3.4.2-150200.4.12.1 |
| `libarchive` | openSUSE:Leap 15.4 | All versions | 3.5.1-150400.3.9.1 |

Products: Debian Debian Linux, Fedoraproject Fedora, Libarchive Libarchive, Redhat Codeready Linux Builder, Redhat Enterprise Linux, Redhat Enterprise Linux Eus, Redhat Enterprise Linux for Ibm Z Systems, Redhat Enterprise Linux for Ibm Z Systems Eus, Redhat Enterprise Linux for Power Little Endian, Redhat Enterprise Linux for Power Little Endian Eus, Redhat Enterprise Linux Server Aus, Redhat Enterprise Linux Server for Power Little Endian Update Services for Sap Solutions, Redhat Enterprise Linux Server Tus, Splunk Universal Forwarder.

## How do I fix CVE-2021-31566?

Apply the vendor's patch.

## Is CVE-2021-31566 being exploited?

There is no known exploitation of CVE-2021-31566 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-31566 and fix it if it is affected.

What it is: CVE-2021-31566 is a high-severity path traversal vulnerability in Debian Debian Linux, published on 23 Aug 2022. 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: There is no known exploitation of CVE-2021-31566 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2021-31566/ (Markdown: https://insights.sbomify.com/CVE-2021-31566/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-31566
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-31566
- OSV: https://osv.dev/vulnerability/CVE-2021-31566

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-31566/
Summaries are generated and may contain mistakes; the official description above is the record.