Junrar: LocalFolderExtractor mkdir escape allows directory creation outside extraction root

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

3.7 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS

• CVE-2026-86071: 0.36% estimated exploitation activity in the next 30 days; percentile 30.14 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary LocalFolderExtractor validates only the final canonical file path before extraction. However, makeFile() creates intermediate directories one path segment at a time without checking whether each created directory remains inside the destination folder. A malicious RAR entry can make the final file path resolve inside the extraction destination, while causing intermediate mkdir() calls to create attacker-chosen directories outside the extraction root. This is an extraction root escape via unchecked intermediate directory creation. The default impact is directory creation outside the intended destination, not unconditional arbitrary file content write. Affected Code - src/main/java/com/github/junrar/LocalFolderExtractor.java - createFile() checks only the final canonical path. - makeFile() calls dir.mkdir() for each intermediate segment without containment checks. Relevant code flow: Impact An attacker who can supply a malicious RAR archive can create directories outside the…

Published by the source

17 Sep 2026, 16:30 UTC

Last modified by the source

17 Sep 2026, 16:45 UTC

Source last checked

26 Oct 2026, 16:55 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-89m4-43j5-vhhx

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-89m4-43j5-vhhx

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# Patch Next advisory brief: CVE-2026-86071

Advisory: Junrar: LocalFolderExtractor mkdir escape allows directory creation outside extraction root
IDs: CVE-2026-86071, GHSA-89m4-43j5-vhhx
Record: https://patchnext.com/advisories/cve-2026-86071 (revision 2, source checked 26 Oct 2026, 16:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: com.github.junrar:junrar 7.6.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven com.github.junrar:junrar: affected <= 7.6.0; fixed in 7.6.1

## Suggested inspection (read-only)
- Maven com.github.junrar:junrar: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on com.github.junrar:junrar.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-89m4-43j5-vhhx (OSV record GHSA-89m4-43j5-vhhx lists affected ranges: Maven com.github.junrar:junrar >=0 <7.6.1 (fixed))
- Verified: https://github.com/advisories/GHSA-89m4-43j5-vhhx (GitHub-reviewed advisory GHSA-89m4-43j5-vhhx lists affected ranges: Maven com.github.junrar:junrar >=0 <=7.6.0)

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