CVE-2026-34835

4.8 MEDIUM
Published: April 02, 2026 Modified: April 03, 2026
View on NVD

Description

Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Request parses the Host header using an AUTHORITY regular expression that accepts characters not permitted in RFC-compliant hostnames, including /, ?, #, and @. Because req.host returns the full parsed value, applications that validate hosts using naive prefix or suffix checks can be bypassed. This can lead to host header poisoning in applications that use req.host, req.url, or req.base_url for link generation, redirects, or origin validation. This issue has been patched in versions 3.1.21 and 3.2.6.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/rack/rack/security/advisories/GHSA-g2pf-xv49-m2h5
Source: security-advisories@github.com
Vendor Advisory Exploit Mitigation

1 reference(s) from NVD

Quick Stats

CVSS v3 Score
4.8 / 10.0
EPSS (Exploit Probability)
0.1%
28th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

rack