{"id":"DEBIAN-CVE-2026-55213","details":"h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1, when h2o processes a QPACK instruction sent from the peer over HTTP/3, lib/http3/qpack.c might allocate an on-stack buffer as large as approximately 800 KB by calling alloca, which exceeds the default pthread stack size used by musl libc and causes the h2o server to crash with a segmentation fault while touching the guard page. This issue is fixed in commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1.","modified":"2026-09-29T13:04:10.950101658Z","published":"2026-07-10T21:16:55.497Z","upstream":["CVE-2026-55213"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-55213"}],"affected":[{"package":{"name":"h2o","ecosystem":"Debian:12","purl":"pkg:deb/debian/h2o?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.2.5+dfsg2-10","2.2.5+dfsg2-11","2.2.5+dfsg2-7","2.2.5+dfsg2-8","2.2.5+dfsg2-8.1","2.2.5+dfsg2-8.1~exp1","2.2.5+dfsg2-9"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55213.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:N/I:N/A:H"}]}