What is CVE-2026-34835?

CVE-2026-34835 is a medium-severity vulnerability in Rack, classified under CWE-1286. CVSS score: 4.8/10. Published 2026-04-02.

How severe is CVE-2026-34835?

Medium severity. CVSS v3 base score is 4.8 out of 10.

Vulnerability in Rack

CVE-2026-34835

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-com…

EPSS: 0.002 (35.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N.

Affected products

Rack — versions >= 3.0.0.beta1, < 3.1.21, >= 3.2.0, < 3.2.6

Weakness classification (CWE)

CWE-1286

References

https://github.com/rack/rack/security/advisories/GHSA-g2pf-xv49-m2h5 (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-34835?: CVE-2026-34835 is a medium-severity vulnerability in Rack, classified under CWE-1286. CVSS score: 4.8/10. Published 2026-04-02.
How severe is CVE-2026-34835?: Medium severity. CVSS v3 base score is 4.8 out of 10.