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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
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
Which versions are affected by CVE-2026-86071?
2 open source packages ship an affected version, including com.github.junrar:junrar.
| Package | 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.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-86071 being exploited?
There is no known exploitation of CVE-2026-86071 in the wild and no public exploit code.
Sources
Also known as ECHO-3dd8-1d6e-83c7, GHSA-89m4-43j5-vhhx.