{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-1677","assignerOrgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","state":"PUBLISHED","assignerShortName":"zephyr","dateReserved":"2026-01-30T05:38:22.811Z","datePublished":"2026-05-11T05:52:12.140Z","dateUpdated":"2026-05-11T16:31:22.202Z"},"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","packageName":"Zephyr","product":"Zephyr","repo":"https://github.com/zephyrproject-rtos/zephyr","vendor":"zephyrproject-rtos","versions":[{"lessThanOrEqual":"4.3","status":"affected","version":"*","versionType":"git"}]}],"descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"net:  TLS 1.2 connections allowed  on TLS 1.3 sockets"}],"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."}],"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":{"orgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","shortName":"zephyr","dateUpdated":"2026-05-11T05:52:12.140Z"},"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-23r2-m5wx-4rvq"}],"source":{"discovery":"UNKNOWN"},"title":"net:  TLS 1.2 connections allowed  on TLS 1.3 sockets","x_generator":{"engine":"swg-tools/create-cve-info"}},"adp":[{"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"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-05-11T16:31:22.202Z"}}]}}