CVE-2026-55213 (GCVE-0-2026-55213)

Vulnerability from cvelistv5 – Published: 2026-07-10 20:49 – Updated: 2026-07-13 14:14
VLAI
Title
h2o: musl libc stack overflow (QPACK)
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.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-13 14:14 UTC
CWE
  • CWE-789 - Memory Allocation with Excessive Size Value
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7712 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
h2o h2o Affected: < edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1
guessed Create a notification for this product.
Show details on NVD website
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