# CVE-2026-86071: Junrar: LocalFolderExtractor mkdir escape allows directory creation outside extraction root

> Attackers can create directories outside the extraction root via crafted RAR archives, potentially causing filesystem pollution or denial of service.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/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:** 16 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** ECHO-3dd8-1d6e-83c7, GHSA-89m4-43j5-vhhx

## What is CVE-2026-86071?

CVE-2026-86071 is a low-severity path traversal vulnerability in junrar, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Junrar is an open source Java RAR archive library. Prior to version 7.6.1, LocalFolderExtractor in src/main/java/com/github/junrar/LocalFolderExtractor.java can create directories outside the intended extraction root when processing a crafted archive entry. LocalFolderExtractor.createFile() validates only the final canonical file path, while LocalFolderExtractor.makeFile() creates intermediate path segments with unchecked mkdir() calls. An entry can therefore make the final path resolve inside the destination while causing intermediate directory creation outside it, enabling filesystem pollution or file-versus-directory squatting that can make later security-sensitive writes fail. The demonstrated impact is directory creation, not unconditional arbitrary file-content write. This issue is fixed in version 7.6.1.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-86071?

2 open source packages ship an affected version, including com.github.junrar:junrar.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `com.github.junrar:junrar` | Maven | All versions | 7.6.1 |
| `com.github.junrar:junrar` | Maven | All versions | 7.6.1 |

## How do I fix CVE-2026-86071?

Upgrade com.github.junrar:junrar to 7.6.1 or later.

## Is CVE-2026-86071 being exploited?

There is no known exploitation of CVE-2026-86071 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86071 and fix it if it is affected.

What it is: CVE-2026-86071 is a low-severity path traversal vulnerability in junrar, published on 16 Sep 2026. 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-2026-86071 in the wild and no public exploit code.

Affected packages and fixed versions:
- com.github.junrar:junrar (Maven): affected all versions; fixed in 7.6.1
- com.github.junrar:junrar (Maven): affected all versions; fixed in 7.6.1

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-2026-86071/ (Markdown: https://insights.sbomify.com/CVE-2026-86071/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86071
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86071
- OSV: https://osv.dev/vulnerability/CVE-2026-86071

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86071/
Summaries are generated and may contain mistakes; the official description above is the record.