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CVE-2026-34827

7.5 · HIGH

Rack is a modular Ruby web server interface.

Published Apr 2, 2026CWE-400EPSS 0.66%

Overview

CVE-2026-34827 is a high-severity vulnerability. It was published on April 2, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. 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::Multipart::Parser#handle_mime_head parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated String#index searches combined with String#slice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticated attacker can send a crafted multipart/form-data request containing many parts with long backslash-escaped parameter values to trigger excessive CPU usage during multipart parsing. This results in a denial of service condition in Rack applications that accept multipart form data. This issue has been patched in versions 3.1.21 and 3.2.6.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. 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.

References

GitHubgithub.com/rack/rack/security/advisories/GHSA-v6x5-cg8r-vv6xRefaccess.redhat.com/security/cve/CVE-2026-34827Refbugzilla.redhat.com/show_bug.cgi?id=2454501Refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34827.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-34827?

CVE-2026-34827 is a high-severity vulnerability. It was published on April 2, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-34827?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-34827?

Check the references section for vendor advisories, patches, and mitigation guidance. 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-2026-34827?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-34827 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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