{"id":"CVE-2026-55213","summary":"h2o: musl libc stack overflow (QPACK)","details":"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.","aliases":["GHSA-432c-8xmj-frmq"],"modified":"2026-07-16T03:31:00.206677665Z","published":"2026-07-10T20:49:58.764Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55213.json","unresolved_ranges":[{"source":"AFFECTED_FIELD","extracted_events":[{"fixed":"edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1"}]}],"cna_assigner":"GitHub_M","cwe_ids":["CWE-789"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55213.json"},{"type":"ADVISORY","url":"https://github.com/h2o/h2o/security/advisories/GHSA-432c-8xmj-frmq"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55213"},{"type":"FIX","url":"https://github.com/h2o/h2o/commit/edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/h2o/h2o","events":[{"introduced":"0"},{"fixed":"edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1"}],"database_specific":{"source":"REFERENCES"}}],"versions":["v1.7.0","v1.7.0-beta5","v1.7.0-beta4","v1.7.0-beta3","v1.7.0-beta2","v1.7.0-beta1","v1.6.0","v1.6.0-beta2","v1.6.0-beta1","v1.5.3","v1.5.2","v1.5.1","v1.5.0","v1.5.0-beta4","v1.5.0-beta3","v1.5.0-beta2","v1.5.0-beta1","v1.4.2","v1.4.1","v1.4.0","v1.3.1","v1.3.0","v1.3.0-beta1","v1.2.0","v1.1.1","v1.1.0","v1.0.1","v0.9.2","v0.9.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-55213.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}