# CVE-2026-82455: RubyGems before 4.0.13 Path Traversal via Symlink Resolution

CVE-2026-82455 is fixed in rubygems on 1 platform by DEBIAN-CVE-2026-82455 (version 4.0.15-2), released September 10, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-82455
- Priority: High
- CVSS: 7.1 (Moderate)
- EPSS: n/a
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 29, 2026
- Weakness: Improper Link Resolution Before File Access ('Link Following')
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-82455

## Description

RubyGems fails to re-validate path containment after filesystem symlink resolution during gem extraction. When a pre-existing symlink inside the destination directory points outside the extraction root, extracted files that appear to be written under the destination directory can instead be written outside of it, breaking the extraction safety boundary. The fix resolves the real path of the parent directory before writing and raises Gem::Package::PathError if it escapes the destination directory.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | rubygems Debian 14 | 4.0.15-2 | [DEBIAN-CVE-2026-82455](https://patchblox.com/security/data/fix/linux/debian-cve-2026-82455.md) | Sep 10, 2026 |

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Data as of 2026-11-09T19:38:12Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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