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CVE-2026-55213

h2o: musl libc stack overflow (QPACK) PUBLISHED

Description (CNA)

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 (CNA)

Vendor / productVersions
h2o / h2oaffected < edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1

CWE

CWE-789

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.