{"id":"CVE-2026-1677","state":"PUBLISHED","title":"net:  TLS 1.2 connections allowed  on TLS 1.3 sockets","description":"Zephyr sockets created with `IPPROTO_TLS_1_3` can still negotiate a TLS 1.2 connection when both TLS versions are enabled in Kconfig, because the socket-level protocol selection is not propagated to mbedTLS (e.g. via `mbedtls_ssl_conf_min_tls_version`). The ClientHello advertises both versions and the peer can establish TLS 1.2, so applications that assumed `IPPROTO_TLS_1_3` enforces TLS 1.3 may silently use TLS 1.2 and remain exposed to TLS 1.2-specific weaknesses. As a workaround, the `TLS_CIPHERSUITE_LIST` socket option can be restricted to TLS 1.3-only cipher suites.","publishedAt":"2026-05-11T05:52:12.140Z","updatedAt":"2026-10-15T22:10:21.970Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","source":"zephyr"},"assigner":"zephyr","products":["zephyrproject-rtos Zephyr"],"affected":[{"vendor":"zephyrproject-rtos","product":"Zephyr","packageName":"Zephyr","defaultStatus":"unaffected","versions":[{"version":"*","status":"affected","lessThan":"4.4.0","versionType":"git"}],"repo":"https://github.com/zephyrproject-rtos/zephyr"}],"references":["https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-23r2-m5wx-4rvq"],"weaknesses":["CWE-757"],"ingestedAt":"2026-10-29T20:11:10.572Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/1xxx/CVE-2026-1677.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-1677","state":"PUBLISHED","datePublished":"2026-05-11T05:52:12.140Z","dateUpdated":"2026-10-15T22:10:21.970Z","assignerShortName":"zephyr","assignerOrgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","dateReserved":"2026-01-30T05:38:22.811Z"},"containers":{"cna":{"title":"net:  TLS 1.2 connections allowed  on TLS 1.3 sockets","descriptions":[{"lang":"en","value":"Zephyr sockets created with `IPPROTO_TLS_1_3` can still negotiate a TLS 1.2 connection when both TLS versions are enabled in Kconfig, because the socket-level protocol selection is not propagated to mbedTLS (e.g. via `mbedtls_ssl_conf_min_tls_version`). The ClientHello advertises both versions and the peer can establish TLS 1.2, so applications that assumed `IPPROTO_TLS_1_3` enforces TLS 1.3 may silently use TLS 1.2 and remain exposed to TLS 1.2-specific weaknesses. As a workaround, the `TLS_CIPHERSUITE_LIST` socket option can be restricted to TLS 1.3-only cipher suites."}],"affected":[{"vendor":"zephyrproject-rtos","product":"Zephyr","packageName":"Zephyr","defaultStatus":"unaffected","versions":[{"version":"*","status":"affected","lessThan":"4.4.0","versionType":"git"}],"repo":"https://github.com/zephyrproject-rtos/zephyr"}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-23r2-m5wx-4rvq"}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","version":"3.1"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-757","description":"Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"zephyr","orgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","dateUpdated":"2026-10-15T22:10:21.970Z"},"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"swg-tools/create-cve-info"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-23r2-m5wx-4rvq","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-11T16:31:12.694213Z","id":"CVE-2026-1677","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-11T16:31:22.202Z"}}]}}}