{"id":"CVE-2026-59993","state":"PUBLISHED","title":"Picotls has NULL pointer dereference during handshake, when running as a client","description":"Picotls is a TLS protocol library that allows users select different crypto backends based on their use case. In affected revisions through 44bc503, when picotls is used as a `client-side TLS stack`, a peer can send a `HelloRetryRequest` followed by a `spoofed Hello message` that causes a null-pointer dereference. This can terminate the consuming process, including a process performing other work, resulting in denial of service. This issue is fixed in commit a06ca41.","publishedAt":"2026-10-30T21:01:54.818Z","updatedAt":"2026-10-30T21:01:54.818Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["h2o picotls"],"affected":[{"vendor":"h2o","product":"picotls","versions":[{"version":"< a06ca417a16f9126808bf5cabe6c5e6e0f16ecae","status":"affected"}]}],"references":["https://github.com/h2o/picotls/security/advisories/GHSA-2xcv-h2pg-m99c","https://github.com/h2o/picotls/pull/608","https://github.com/h2o/picotls/commit/a06ca417a16f9126808bf5cabe6c5e6e0f16ecae"],"weaknesses":["CWE-476"],"ingestedAt":"2026-10-30T21:16:06.312Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/59xxx/CVE-2026-59993.json","commit":"6329c9a5f29e89d72255f2ba3cdd9f05da71e0aa","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-59993","state":"PUBLISHED","datePublished":"2026-10-30T21:01:54.818Z","dateUpdated":"2026-10-30T21:01:54.818Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-07T19:41:00.005Z"},"containers":{"cna":{"title":"Picotls has NULL pointer dereference during handshake, when running as a client","descriptions":[{"lang":"en","value":"Picotls is a TLS protocol library that allows users select different crypto backends based on their use case. In affected revisions through 44bc503, when picotls is used as a `client-side TLS stack`, a peer can send a `HelloRetryRequest` followed by a `spoofed Hello message` that causes a null-pointer dereference. This can terminate the consuming process, including a process performing other work, resulting in denial of service. This issue is fixed in commit a06ca41."}],"affected":[{"vendor":"h2o","product":"picotls","versions":[{"version":"< a06ca417a16f9126808bf5cabe6c5e6e0f16ecae","status":"affected"}]}],"references":[{"url":"https://github.com/h2o/picotls/security/advisories/GHSA-2xcv-h2pg-m99c","name":"https://github.com/h2o/picotls/security/advisories/GHSA-2xcv-h2pg-m99c","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/h2o/picotls/pull/608","name":"https://github.com/h2o/picotls/pull/608","tags":["x_refsource_MISC"]},{"url":"https://github.com/h2o/picotls/commit/a06ca417a16f9126808bf5cabe6c5e6e0f16ecae","name":"https://github.com/h2o/picotls/commit/a06ca417a16f9126808bf5cabe6c5e6e0f16ecae","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-476","lang":"en","description":"CWE-476: NULL Pointer Dereference","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-30T21:01:54.818Z"},"source":{"advisory":"GHSA-2xcv-h2pg-m99c","discovery":"UNKNOWN"}}}}}