CVE-2026-55213
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
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.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| h2o | h2o | < edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1 | affected |
Weaknesses
- CWE-789: CWE-789: Memory Allocation with Excessive Size Value
References
- https://github.com/h2o/h2o/security/advisories/GHSA-432c-8xmj-frmq
- https://github.com/h2o/h2o/commit/edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1
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