{"id":"CVE-2026-44452","state":"PUBLISHED","title":"h2o is vulnerable to heap overrun","description":"h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 8dc37cb, when h2o receives a ClientHello message over TLS or QUIC and it contains a zero-length SNI extension, the h2o server runs over the zero-length hostname while trying to copy the hostname, assuming that it is NULL-terminated. This is a potential denial-of-service attack vector in sense that it might trigger segmentation violation. This issue has been fixed by commit 8dc37cb.","publishedAt":"2026-07-16T22:54:42.914Z","updatedAt":"2026-07-17T14:03:52.757Z","severity":{"score":5.9,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["h2o h2o"],"affected":[{"vendor":"h2o","product":"h2o","versions":[{"version":"< 8dc37cb","status":"affected"}]}],"references":["https://github.com/h2o/h2o/security/advisories/GHSA-w68q-rqwx-7wvq","https://github.com/h2o/h2o/commit/8dc37cb1e6171f7f772667618ea440696fed82c3"],"weaknesses":["CWE-125","CWE-170"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/44xxx/CVE-2026-44452.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-44452","state":"PUBLISHED","datePublished":"2026-07-16T22:54:42.914Z","dateUpdated":"2026-07-17T14:03:52.757Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-05-06T15:49:25.192Z"},"containers":{"cna":{"title":"h2o is vulnerable to heap overrun","descriptions":[{"lang":"en","value":"h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 8dc37cb, when h2o receives a ClientHello message over TLS or QUIC and it contains a zero-length SNI extension, the h2o server runs over the zero-length hostname while trying to copy the hostname, assuming that it is NULL-terminated. This is a potential denial-of-service attack vector in sense that it might trigger segmentation violation. This issue has been fixed by commit 8dc37cb."}],"affected":[{"vendor":"h2o","product":"h2o","versions":[{"version":"< 8dc37cb","status":"affected"}]}],"references":[{"url":"https://github.com/h2o/h2o/security/advisories/GHSA-w68q-rqwx-7wvq","name":"https://github.com/h2o/h2o/security/advisories/GHSA-w68q-rqwx-7wvq","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/h2o/h2o/commit/8dc37cb1e6171f7f772667618ea440696fed82c3","name":"https://github.com/h2o/h2o/commit/8dc37cb1e6171f7f772667618ea440696fed82c3","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":5.9,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-125","lang":"en","description":"CWE-125: Out-of-bounds Read","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-170","lang":"en","description":"CWE-170: Improper Null Termination","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-16T22:54:42.914Z"},"source":{"advisory":"GHSA-w68q-rqwx-7wvq","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-17T14:03:32.725590Z","id":"CVE-2026-44452","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-17T14:03:52.757Z"}}]}}}