CVE-2026-34763 Rack: Rack::Directory info disclosure and DoS via unescaped regex interpolation
Attackers can expose full filesystem paths and cause denial of service in Rack::Directory due to unescaped regex interpolation of the root path.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-34763?
CVE-2026-34763 is a medium-severity vulnerability in rack, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Directory interpolates the configured root path directly into a regular expression when deriving the displayed directory path. If root contains regex metacharacters such as +, *, or ., the prefix stripping can fail and the generated directory listing may expose the full filesystem path in the HTML output. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
Weakness: CWE-625
Which versions are affected by CVE-2026-34763?
6 open source packages ship an affected version, including rack. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
rack RubyGems | All versions | 2.2.23 |
rack RubyGems | All versions | 2.2.23 |
rack RubyGems | From 3.0.0.beta1 | 3.1.21 |
rack RubyGems | From 3.0.0.beta1 | 3.1.21 |
rack RubyGems | From 3.2.0 | 3.2.6 |
rack RubyGems | From 3.2.0 | 3.2.6 |
Products include Rack Rack.
How do I fix CVE-2026-34763?
Upgrade rack to a fixed version for your release line: 2.2.23, 3.1.21 or 3.2.6.
Is CVE-2026-34763 being exploited?
There is no known exploitation of CVE-2026-34763 in the wild and no public exploit code.
Other vulnerabilities in rack
- CVE-2026-34785 Rack: Local file inclusion in `Rack::Static` via URL Prefix Matching
- CVE-2026-34827 Rack: Algorithmic-Complexity DoS in Rack::Multipart::Parser
- CVE-2026-34829 Rack: Denial of Service via Unbounded Multipart File Upload Without Content-Length
- CVE-2026-22860 Rack has a Directory Traversal via Rack:Directory
- CVE-2025-61919 Rack is vulnerable to a memory-exhaustion DoS through unbounded URL-encoded body parsing
Sources
Also known as DEBIAN-CVE-2026-34763, GHSA-7mqq-6cf9-v2qp, MINI-5jv8-pc96-jvx6, MINI-6w4q-43j9-pg95, MINI-78j4-q88f-gj4p, MINI-7w4m-296h-gppm and 21 more.