CVE-2026-22860: Rack has a Directory Traversal via Rack:Directory

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-02-18 · updated 2026-07-15
Weakness: CWE-22

Description

Rack is a modular Ruby web server interface. Prior to versions 2.2.22, 3.1.20, and 3.2.5, `Rack::Directory`’s path check used a string prefix match on the expanded path. A request like `/../root_example/` can escape the configured root if the target path starts with the root string, allowing directory listing outside the intended root. Versions 2.2.22, 3.1.20, and 3.2.5 fix the issue.

Affected products

rack: before 2.2.22; from 3.0.0 before 3.1.20; from 3.2.0 before 3.2.5 — fixed in 2.2.22, 3.1.20, 3.2.5
Rubygems Rack: before 2.2.22; from 3.0.0.beta1 before 3.1.20; from 3.2.0 before 3.2.5; 0.1.0, 0.2.0, 0.3.0, 0.4.0, 0.9.0, 0.9.1 (+166) — fixed in 2.2.22, 3.1.20, 3.2.5

How to fix

Upgrade to a fixed version: rack 2.2.22, 3.1.20, 3.2.5; Rubygems Rack 2.2.22, 3.1.20, 3.2.5. Check the vendor advisory for mitigations.

References

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