DEBIAN-CVE-2026-44453
h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 6b5370d, h2o is vulnerable to a Denial of Service attack when calling alloca under certain conditions. When serving static files, h2o builds the file path on stack, by calling alloca. The maximum size of the memory allocated using alloca can be as huge as ~600KB, which exceeds the default pthread stack size used by musl libc (128KB). If the amount of memory allocated by alloca exceeds the stack size, the h2o server crashes with a segmentation fault, while it tries to touch the guard page. This issue has been fixed by commit 6b5370d.
DEBIAN-CVE-2026-44453
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-2026-44453
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-2026-44453.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
]Publisher severity
No explicit severity was provided.
- Event
- #56501 · Revision 1
- Added to Heist Feed
- Publisher date