Improper Validation of Syntactic Correctness of Input The advisory has been revoked - it doesn't affect any version of package ruby-rack (opens in a new tab)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN11-RUBYRACK-15922769
- published7 Apr 2026
- disclosed2 Apr 2026
Introduced: 2 Apr 2026
CVE-2026-34835 (opens in a new tab)Amendment
The Debian security team deemed this advisory irrelevant for Debian:11.
NVD Description
Note: Versions mentioned in the description apply only to the upstream ruby-rack package and not the ruby-rack package as distributed by Debian.
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.