h2o -- stack overflow serving static files on musl libc

2026-06-11 · CVE-2026-44453 · VuXML entry

h2o project reports: When serving static files, h2o can allocate a file path on the stack using alloca. On systems using musl libc, a large allocation can exceed the default pthread stack size and crash the server, causing a denial of service.

Affected versions

• h2o < 20260609

By system

1 still vulnerable, 1 fixed. Where VuXML applies (FreeBSD, DragonFly, FreeBSD's derivatives) a port is vulnerable while its version is in a range; pkgsrc says itself whether it lists a CVE of this advisory; OpenBSD and MidnightBSD keep no list this site reads, so their row is only an estimate: FreeBSD's ranges applied to upstream's version.