CVE-2026-34763 — Permissive Regular Expression in Rack

CWE-625 — Permissive Regular ExpressionCWE-41 — Improper Resolution of Path Equivalence10 documents8 sources
Severity
5.3MEDIUMNVD
EPSS
0.0%
top 88.68%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
1
Rack
Timeline
PublishedApr 2
Latest updateApr 17

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.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NExploitability: 3.9 | Impact: 1.4

Affected Packages2 packages

▶CVEListV5rack/rack< 2.2.23+2
▶RubyGemsrack/rack3.0.0.beta1 — 3.1.21+2

🔴Vulnerability Details

5
OSV
CVE-2026-34763: (Rack is a modular Ruby web server interface↗2026-04-03
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CVEList
Rack: Rack::Directory info disclosure and DoS via unescaped regex interpolation↗2026-04-02
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OSV
CVE-2026-34763: Rack is a modular Ruby web server interface↗2026-04-02
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GHSA
Rack has a root directory disclosure via unescaped regex interpolation in Rack::Directory↗2026-04-02
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OSV
Rack has a root directory disclosure via unescaped regex interpolation in Rack::Directory↗2026-04-02
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📋Vendor Advisories

3
Ubuntu
Rack vulnerabilities↗2026-04-17
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Red Hat
rack: Rack: Information disclosure via regular expression metacharacters in root path↗2026-04-02
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Debian
CVE-2026-34763: ruby-rack - Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, a...↗2026
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🕵️Threat Intelligence

1
Wiz
CVE-2026-34763 Impact, Exploitability, and Mitigation Steps | Wiz↗
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CVE-2026-34763 — Permissive Regular Expression in Rack | cvebase