{"id":"CVE-2026-75806","state":"PUBLISHED","title":"Unauthenticated and Undersized DTLS 1.2 AEAD Record Causes DoS","description":"Issue summary: An established DTLS 1.2 association using an AEAD cipher suite\ncan be terminated by a single unauthenticated datagram whose encrypted\nfragment is shorter than the mandatory explicit IV and authentication tag\noverhead.\n\nImpact summary: An attacker who can send a datagram that is routed to an\nexisting DTLS 1.2 association can tear that association down without knowing\nany key material. This is a Denial of Service limited to the targeted\nassociation. There is no memory safety or confidentiality impact.\n\nCWE: CWE-1284: Improper Validation of Specified Quantity in Input\n\nDescription: In TLS 1.2 and DTLS 1.2 every record protected by an AEAD cipher\nsuite carries an explicit IV followed by the ciphertext and an authentication\ntag. When decrypting such a record the record layer passed the record length to\nthe cipher implementation before checking that the record was long enough to\ncontain the explicit IV and the tag. For a record shorter than that overhead the\ncipher implementation rejected the impossible length, and the record layer\ntreated this as an internal failure and raised a fatal internal_error alert\ninstead of treating the record as one that failed authentication.\n\nIn TLS 1.2 the same record causes a fatal internal_error alert instead of the\nexpected bad_record_mac alert. Since any undecryptable record already\nterminates a TLS connection, this is a protocol conformance issue rather than\na security issue in TLS.\n\nThe fix validates the record length against the explicit IV and tag length\nbefore any AEAD processing, so that TLS reports bad_record_mac and DTLS\nsilently discards the record.\n\nFIPS impact: no\nThe affected code is outside the FIPS module boundary.","publishedAt":"2026-09-29T15:32:21.457Z","updatedAt":"2026-09-29T16:53:23.785Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","source":"CISA-ADP"},"assigner":"openssl","products":["OpenSSL OpenSSL"],"affected":[{"vendor":"OpenSSL","product":"OpenSSL","defaultStatus":"unaffected","versions":[{"version":"4.0.0","status":"affected","lessThan":"4.0.3","versionType":"semver"},{"version":"3.6.0","status":"affected","lessThan":"3.6.5","versionType":"semver"},{"version":"3.5.0","status":"affected","lessThan":"3.5.9","versionType":"semver"},{"version":"3.4.0","status":"affected","lessThan":"3.4.8","versionType":"semver"},{"version":"3.0.0","status":"affected","lessThan":"3.0.23","versionType":"semver"},{"version":"1.1.1","status":"affected","lessThan":"1.1.1zj","versionType":"custom"}]}],"references":["https://openssl-library.org/news/secadv/20260929.txt","https://github.com/openssl/openssl/commit/04728a289a823e68137f88da016cb9ede307217d","https://github.com/openssl/openssl/commit/050b275cd671a6eed1d6457642d41a5a77aab972","https://github.com/openssl/openssl/commit/3a4589d015a9049d47b66f186cf50a8711343a1d","https://github.com/openssl/openssl/commit/5af82fefbaf2b5fec2fc0e1d87f112844902f01d"],"weaknesses":["CWE-1284"],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/75xxx/CVE-2026-75806.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-75806","state":"PUBLISHED","datePublished":"2026-09-29T15:32:21.457Z","dateUpdated":"2026-09-29T16:53:23.785Z","assignerShortName":"openssl","assignerOrgId":"3a12439a-ef3a-4c79-92e6-6081a721f1e5","dateReserved":"2026-08-18T09:34:32.659Z"},"containers":{"cna":{"title":"Unauthenticated and Undersized DTLS 1.2 AEAD Record Causes DoS","descriptions":[{"lang":"en","value":"Issue summary: An established DTLS 1.2 association using an AEAD cipher suite\ncan be terminated by a single unauthenticated datagram whose encrypted\nfragment is shorter than the mandatory explicit IV and authentication tag\noverhead.\n\nImpact summary: An attacker who can send a datagram that is routed to an\nexisting DTLS 1.2 association can tear that association down without knowing\nany key material. This is a Denial of Service limited to the targeted\nassociation. There is no memory safety or confidentiality impact.\n\nCWE: CWE-1284: Improper Validation of Specified Quantity in Input\n\nDescription: In TLS 1.2 and DTLS 1.2 every record protected by an AEAD cipher\nsuite carries an explicit IV followed by the ciphertext and an authentication\ntag. When decrypting such a record the record layer passed the record length to\nthe cipher implementation before checking that the record was long enough to\ncontain the explicit IV and the tag. For a record shorter than that overhead the\ncipher implementation rejected the impossible length, and the record layer\ntreated this as an internal failure and raised a fatal internal_error alert\ninstead of treating the record as one that failed authentication.\n\nIn TLS 1.2 the same record causes a fatal internal_error alert instead of the\nexpected bad_record_mac alert. Since any undecryptable record already\nterminates a TLS connection, this is a protocol conformance issue rather than\na security issue in TLS.\n\nThe fix validates the record length against the explicit IV and tag length\nbefore any AEAD processing, so that TLS reports bad_record_mac and DTLS\nsilently discards the record.\n\nFIPS impact: no\nThe affected code is outside the FIPS module boundary."}],"affected":[{"vendor":"OpenSSL","product":"OpenSSL","defaultStatus":"unaffected","versions":[{"version":"4.0.0","status":"affected","lessThan":"4.0.3","versionType":"semver"},{"version":"3.6.0","status":"affected","lessThan":"3.6.5","versionType":"semver"},{"version":"3.5.0","status":"affected","lessThan":"3.5.9","versionType":"semver"},{"version":"3.4.0","status":"affected","lessThan":"3.4.8","versionType":"semver"},{"version":"3.0.0","status":"affected","lessThan":"3.0.23","versionType":"semver"},{"version":"1.1.1","status":"affected","lessThan":"1.1.1zj","versionType":"custom"}]}],"references":[{"url":"https://openssl-library.org/news/secadv/20260929.txt","name":"OpenSSL Advisory","tags":["vendor-advisory"]},{"url":"https://github.com/openssl/openssl/commit/04728a289a823e68137f88da016cb9ede307217d","name":"4.0.3 git commit","tags":["patch"]},{"url":"https://github.com/openssl/openssl/commit/050b275cd671a6eed1d6457642d41a5a77aab972","name":"3.6.5 git commit","tags":["patch"]},{"url":"https://github.com/openssl/openssl/commit/3a4589d015a9049d47b66f186cf50a8711343a1d","name":"3.5.9 git commit","tags":["patch"]},{"url":"https://github.com/openssl/openssl/commit/5af82fefbaf2b5fec2fc0e1d87f112844902f01d","name":"3.4.8 git commit","tags":["patch"]}],"metrics":[{"format":"other","other":{"content":{"text":"Low"},"type":"https://openssl-library.org/policies/general/security-policy/"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-1284","description":"CWE-1284 Improper Validation of Specified Quantity in Input","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"openssl","orgId":"3a12439a-ef3a-4c79-92e6-6081a721f1e5","dateUpdated":"2026-09-29T15:32:21.457Z"},"credits":[{"lang":"en","type":"reporter","value":"Mounir Idrassi"},{"lang":"en","type":"remediation developer","value":"Mounir Idrassi"}],"datePublic":"2026-09-29T14:21:57.000Z","source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 0.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":5.3,"attackVector":"NETWORK","baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"LOW","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-09-29T16:52:47.298458Z","id":"CVE-2026-75806","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-29T16:53:23.785Z"}}]}}}