CVE-2026-55213
CVE-2026-55213 · h2o: musl libc stack overflow (QPACK)
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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.
CVSS 7.5 · High · EPSS 0.5%
- Published
- Updated
Stack: system
Affected products and versions
h2o
- Versions
- < edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1: Affected
No fix published
h2o 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
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
h2o Ubuntu:Pro:18.04:LTS
- Versions
- 2.2.3+dfsg-2
- 2.2.4+dfsg-1
- 2.2.4+dfsg-1build1
- 2.2.4+dfsg-1ubuntu0.1~esm2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
h2o Ubuntu:Pro:20.04:LTS
- Versions
- 2.2.5+dfsg2-3
- 2.2.5+dfsg2-3build1
- 2.2.5+dfsg2-3ubuntu0.1~esm1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
h2o Ubuntu:Pro:22.04:LTS
- Versions
- 2.2.5+dfsg2-6
- 2.2.5+dfsg2-6.1
- 2.2.5+dfsg2-6.1ubuntu1
- 2.2.5+dfsg2-6.1ubuntu2
- 2.2.5+dfsg2-6.1ubuntu2+esm1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
h2o Ubuntu:24.04:LTS
- Versions
- 2.2.5+dfsg2-7
- 2.2.5+dfsg2-8
- 2.2.5+dfsg2-8.1ubuntu1
- 2.2.5+dfsg2-8.1ubuntu2
- 2.2.5+dfsg2-8.1ubuntu3
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
dnsdist Ubuntu:Pro:24.04:LTS
- Versions
- 1.8.0-1
- 1.8.2-1
- 1.8.2-2
- 1.8.2-3
- 1.8.3-1
- 1.8.3-2
- 1.8.3-2build1
- 1.8.3-2build2
- 1.8.3-2ubuntu0.1~esm1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published