{"id":"DEBIAN-CVE-2026-34831","details":"Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Files#fail sets the Content-Length response header using String#size instead of String#bytesize. When the response body contains multibyte UTF-8 characters, the declared Content-Length is smaller than the number of bytes actually sent on the wire. Because Rack::Files reflects the requested path in 404 responses, an attacker can trigger this mismatch by requesting a non-existent path containing percent-encoded UTF-8 characters. This results in incorrect HTTP response framing and may cause response desynchronization in deployments that rely on the incorrect Content-Length value. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.","modified":"2026-09-11T05:01:06.870592985Z","published":"2026-04-02T17:16:26.420Z","upstream":["CVE-2026-34831"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-34831"}],"affected":[{"package":{"name":"ruby-rack","ecosystem":"Debian:12","purl":"pkg:deb/debian/ruby-rack?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.22-0+deb12u2"}]}],"versions":["2.2.13-1~deb12u1","2.2.20-0+deb12u1","2.2.22-0+deb12u1","2.2.6.4-1","2.2.6.4-1+deb12u1","2.2.7-1","2.2.7-1.1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-34831.json"}},{"package":{"name":"ruby-rack","ecosystem":"Debian:13","purl":"pkg:deb/debian/ruby-rack?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.20-0+deb13u2"}]}],"versions":["3.1.16-0.1","3.1.18-1","3.1.18-1~deb13u1","3.1.20-0+deb13u1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-34831.json"}},{"package":{"name":"ruby-rack","ecosystem":"Debian:14","purl":"pkg:deb/debian/ruby-rack?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.6-2"}]}],"versions":["3.1.16-0.1","3.1.18-1","3.1.18-1~deb13u1","3.2.4-1","3.2.5-1","3.2.5-2","3.2.6-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-34831.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"}]}