# CVE-2026-34763: Rack Rack::Directory information disclosure via unescaped regex interpolation

Source: https://junglewise.ai/threats/cve-2026-34763-rack-rack-directory-information-disclosure-via-unescaped-regex  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-02. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-34763 · Severity: medium · CVSS 5.3 · Published 2026-04-02

Rack is a foundational software component used by many Ruby-based web applications to handle web requests. A vulnerability in its directory listing feature can cause the server to accidentally reveal its internal file system structure to any visitor. This exposure of internal paths could help an attacker map out the server's layout, potentially revealing usernames or sensitive deployment details.

Technologies: [rack (RubyGems)](https://junglewise.ai/threats/technologies/rack). Vendors: [RubyGems](https://junglewise.ai/threats/vendors/rubygems).

## Quick answers

**Is CVE-2026-34763 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34763 being exploited in the wild.

**How severe is CVE-2026-34763?** Medium severity, with a CVSS score of 5.3, published 2 April 2026.

**Which products and versions are affected?** rack (RubyGems) ECOSYSTEM:introduced=0,fixed=2.2.23.

**Is there a fix for CVE-2026-34763?** Yes. rack (RubyGems): upgrade to 2.2.23 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-34763 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-34763?** Check whether you run rack (RubyGems) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- rack (RubyGems): upgrade to 2.2.23 or later

  ```sh
  bundle update rack
  ```


## Technical details

The vulnerability exists in the Rack::Directory component where the developer-configured 'root' path is interpolated directly into a regular expression without escaping. Specifically, Rack::Directory::DirectoryBody#each uses a regex to strip the root prefix from the absolute path before rendering it to the user. If the root path contains regex metacharacters (such as +, *, or .), the prefix stripping can fail. This results in the full, absolute filesystem path being leaked in the HTML directory listing instead of the relative path. The issue is reachable over the network without authentication if directory listing is enabled. Patches are available in versions 2.2.23, 3.1.21, and 3.2.6.

## Affected products

- Rack Rack < 2.2.23, >= 3.0.0 < 3.1.21, >= 3.2.0 < 3.2.6

## Identifiers

- CVE-2026-34763
- GHSA-7mqq-6cf9-v2qp

## Timeline

- 2026-04-01: advisory: GitHub Security Advisory published by maintainers
- 2026-04-02: disclosed: CVE published to NVD

## References

- [https://github.com/rack/rack/security/advisories/GHSA-7mqq-6cf9-v2qp](https://github.com/rack/rack/security/advisories/GHSA-7mqq-6cf9-v2qp)

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