| Name | CVE-2026-34835 |
| 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. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| ruby-rack (PTS) | bullseye | 2.1.4-3+deb11u2 | fixed |
| bullseye (security) | 2.1.4-3+deb11u6 | fixed | |
| bookworm | 2.2.22-0+deb12u1 | fixed | |
| bookworm (security) | 2.2.22-0+deb12u2 | fixed | |
| trixie (security), trixie | 3.1.20-0+deb13u1 | vulnerable | |
| forky | 3.2.6-2 | fixed | |
| sid | 3.2.6-3 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| ruby-rack | source | experimental | 3.2.6-1 | |||
| ruby-rack | source | bullseye | (not affected) | |||
| ruby-rack | source | bookworm | (not affected) | |||
| ruby-rack | source | (unstable) | 3.2.6-2 |
[bookworm] - ruby-rack <not-affected> (Vulnerable code introduced later)
[bullseye] - ruby-rack <not-affected> (Vulnerable code introduced later)
https://github.com/rack/rack/security/advisories/GHSA-g2pf-xv49-m2h5
Fixed by: https://github.com/rack/rack/commit/224662608dad63b31ba138d7e76e4ca8e42e9fc6 (v3.2.6)
Fixed by: https://github.com/rack/rack/commit/c49558af795b4c1978d16db071c8344db05a2b0d (v3.1.21)