DEBIAN-CVE-2026-55213
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.
DEBIAN-CVE-2026-55213
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:DEBIAN-CVE-2026-55213
h2o
Source reference: /affected/0/package/name
- Affected versions
- 2.2.5+dfsg2-10
Source reference:
/affected/0/versions2.2.5+dfsg2-11Source reference:
/affected/0/versions2.2.5+dfsg2-7Source reference:
/affected/0/versions2.2.5+dfsg2-8Source reference:
/affected/0/versions2.2.5+dfsg2-8.1Source reference:
/affected/0/versions2.2.5+dfsg2-8.1~exp1Source reference:
/affected/0/versions2.2.5+dfsg2-9Source reference:
/affected/0/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "h2o",
"purl": "pkg:deb/debian/h2o?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"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"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55213.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
]Publisher severity
No explicit severity was provided.
- Event
- #57832 · Revision 1
- Added to Heist Feed
- Publisher date