CVE-2026-34835
4.8 · MEDIUMOverview
CVE-2026-34835 is a medium-severity vulnerability affecting rack rack. It was published on April 2, 2026 and has a CVSS 3.1 base score of 4.8 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 4.8, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from rack. Update rack to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| rack | rack | >= 3.0.0, < 3.1.21 | Affected |
Frequently Asked Questions
What is CVE-2026-34835?
CVE-2026-34835 is a medium-severity vulnerability affecting rack rack. It was published on April 2, 2026 and has a CVSS 3.1 base score of 4.8 (MEDIUM).
How severe is CVE-2026-34835?
This vulnerability has a CVSS 3.1 base score of 4.8, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-34835?
Check the references section for vendor advisories and patches from rack. Update rack to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-34835?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-34835 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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