{"id":"DEBIAN-CVE-2026-91920","details":"A flaw was found in the ChunkReader component of the Undertow web server, which is used to handle chunked transfer encoding in HTTP requests. The issue occurs because a security check for the chunk size is performed before the value is shifted, allowing a specifically crafted 15-digit chunk size to bypass the limit and overflow into internal state flags. This can cause the server to terminate a request body prematurely and interpret the remaining data as a separate, smuggled request.","modified":"2026-11-04T09:47:34.293935734Z","published":"2026-10-30T02:17:10.140Z","upstream":["CVE-2026-91920"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-91920"}],"affected":[{"package":{"name":"undertow","ecosystem":"Debian:14","purl":"pkg:deb/debian/undertow?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.11-1","1.3.16-1","1.3.19-1","1.3.21-1","1.3.23-1","1.3.4-1","1.3.5-1","1.3.7-1","1.4.0-1","1.4.1-1","1.4.18-1","1.4.20-1","1.4.21-1","1.4.21-2","1.4.22-1","1.4.23-1","1.4.23-2","1.4.23-3","1.4.25-1","1.4.25-2","1.4.3-1","1.4.4-1","1.4.6-1","1.4.7-1","1.4.8-1","2.0.23-1","2.0.25-1","2.0.26-1","2.0.27-1","2.0.28-1","2.0.29-1","2.0.30-1","2.1.0-1","2.1.1-1","2.1.3-1","2.2.0-1","2.2.10-1","2.2.12-1","2.2.13-1","2.2.14-1","2.2.16-1","2.2.17-1","2.2.18-1","2.2.19-1","2.2.2-1","2.2.20-1","2.2.21-1","2.2.3-1","2.2.4-1","2.2.5-1","2.2.8-1","2.3.18-1","2.3.18-2","2.3.20-1","2.3.8-1","2.3.8-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-91920.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L"}]}