CVSS 3.1
7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVE-2026-55213
High (7.5). EPSS 0.5% chance of exploitation in the next 30 days.
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.
Severity
- EPSS
- 0.5% chance of exploitation in the next 30 days; higher than 42% of CVEs (scores of 2026-10-31)
- CWE
- CWE-789
- Published
- Modified
- Record from
- the NVD, synced