{"id":"CVE-2026-63072","state":"PUBLISHED","title":"Heap Buffer Overflow in CMS Key Unwrapping","description":"Issue summary: OpenSSL CMS decryption sizes the key-unwrap output buffer based\non querying the unwrapped key size, but the AES-WRAP-PAD unwrap primitive\ncan write and cleanse more bytes than that query reports, causing an 8-byte\nout-of-bounds heap write.\n\nImpact summary: An attacker who supplies a crafted CMS message can trigger a\ndeterministic 8-byte out-of-bounds heap write when the victim decrypts it\nwith CMS_decrypt(), corrupting the heap and typically resulting in a Denial\nof Service.\n\nCWE: CWE-787: Out-of-bounds Write\n\nDescription: The key-wrap OID is potentially attacker-controlled on the wire.\nCMS unwrapping allows both id-aesNNN-wrap-pad and id-aesNNN-wrap ciphers.\nAn attacker can take a legitimate message and change a single OID byte to\nselect the padded variant while leaving the message otherwise valid. Since\nthe unwrap key is derived from the recipient's private operation (ECDH key\nagreement or ML-KEM decapsulation), the RFC 5649 integrity check cannot\npass, and the decryption fails with integrity failure.\n\nThe write is a fixed-size (8-byte), fixed-value (zero) heap overflow\nimmediately past the allocation, requires no special configuration, and is\nreachable from the public CMS_decrypt() function. The consequence is\na heap corruption leading to a Denial of Service. The fix in the CMS code\nsizes the unwrap output buffer for the worst case so a failed unwrap cannot\nwrite past the allocation.\n\nFIPS impact: no\n\nAs the CMS code lives outside the FIPS module boundary, no FIPS\nmodules are affected by this CVE.","publishedAt":"2026-08-25T12:59:34.428Z","updatedAt":"2026-08-25T14:29:55.378Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"CISA-ADP"},"assigner":"openssl","products":["OpenSSL OpenSSL"],"affected":[{"vendor":"OpenSSL","product":"OpenSSL","defaultStatus":"unaffected","versions":[{"version":"4.0.0","status":"affected","lessThan":"4.0.2","versionType":"semver"},{"version":"3.6.0","status":"affected","lessThan":"3.6.4","versionType":"semver"},{"version":"3.5.0","status":"affected","lessThan":"3.5.8","versionType":"semver"},{"version":"3.4.0","status":"affected","lessThan":"3.4.7","versionType":"semver"},{"version":"3.0.0","status":"affected","lessThan":"3.0.22","versionType":"semver"},{"version":"1.1.1","status":"affected","lessThan":"1.1.1zi","versionType":"custom"}]}],"references":["https://openssl-library.org/news/secadv/20260825.txt","https://github.com/openssl/openssl/commit/9530a5fd1aacaeccdced4478ea2340a480613335","https://github.com/openssl/openssl/commit/2a3dac874c8057c1f0186849bf1ede1ae7b6b756","https://github.com/openssl/openssl/commit/87784ad619af36b8807c2044b3940006fccc1e42","https://github.com/openssl/openssl/commit/9ec2f6d2ae2bcad907cf7ee38584855bafe4979a","https://github.com/openssl/openssl/commit/a0c8ec557d9cac078f032d76cdf684fe743eb382"],"weaknesses":["CWE-787"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63072.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63072","state":"PUBLISHED","datePublished":"2026-08-25T12:59:34.428Z","dateUpdated":"2026-08-25T14:29:55.378Z","assignerShortName":"openssl","assignerOrgId":"3a12439a-ef3a-4c79-92e6-6081a721f1e5","dateReserved":"2026-07-15T13:10:26.188Z"},"containers":{"cna":{"title":"Heap Buffer Overflow in CMS Key Unwrapping","descriptions":[{"lang":"en","value":"Issue summary: OpenSSL CMS decryption sizes the key-unwrap output buffer based\non querying the unwrapped key size, but the AES-WRAP-PAD unwrap primitive\ncan write and cleanse more bytes than that query reports, causing an 8-byte\nout-of-bounds heap write.\n\nImpact summary: An attacker who supplies a crafted CMS message can trigger a\ndeterministic 8-byte out-of-bounds heap write when the victim decrypts it\nwith CMS_decrypt(), corrupting the heap and typically resulting in a Denial\nof Service.\n\nCWE: CWE-787: Out-of-bounds Write\n\nDescription: The key-wrap OID is potentially attacker-controlled on the wire.\nCMS unwrapping allows both id-aesNNN-wrap-pad and id-aesNNN-wrap ciphers.\nAn attacker can take a legitimate message and change a single OID byte to\nselect the padded variant while leaving the message otherwise valid. Since\nthe unwrap key is derived from the recipient's private operation (ECDH key\nagreement or ML-KEM decapsulation), the RFC 5649 integrity check cannot\npass, and the decryption fails with integrity failure.\n\nThe write is a fixed-size (8-byte), fixed-value (zero) heap overflow\nimmediately past the allocation, requires no special configuration, and is\nreachable from the public CMS_decrypt() function. The consequence is\na heap corruption leading to a Denial of Service. The fix in the CMS code\nsizes the unwrap output buffer for the worst case so a failed unwrap cannot\nwrite past the allocation.\n\nFIPS impact: no\n\nAs the CMS code lives outside the FIPS module boundary, no FIPS\nmodules are affected by this CVE."}],"affected":[{"vendor":"OpenSSL","product":"OpenSSL","defaultStatus":"unaffected","versions":[{"version":"4.0.0","status":"affected","lessThan":"4.0.2","versionType":"semver"},{"version":"3.6.0","status":"affected","lessThan":"3.6.4","versionType":"semver"},{"version":"3.5.0","status":"affected","lessThan":"3.5.8","versionType":"semver"},{"version":"3.4.0","status":"affected","lessThan":"3.4.7","versionType":"semver"},{"version":"3.0.0","status":"affected","lessThan":"3.0.22","versionType":"semver"},{"version":"1.1.1","status":"affected","lessThan":"1.1.1zi","versionType":"custom"}]}],"references":[{"url":"https://openssl-library.org/news/secadv/20260825.txt","name":"OpenSSL Advisory","tags":["vendor-advisory"]},{"url":"https://github.com/openssl/openssl/commit/9530a5fd1aacaeccdced4478ea2340a480613335","name":"4.0.2 git commit","tags":["patch"]},{"url":"https://github.com/openssl/openssl/commit/2a3dac874c8057c1f0186849bf1ede1ae7b6b756","name":"3.6.4 git commit","tags":["patch"]},{"url":"https://github.com/openssl/openssl/commit/87784ad619af36b8807c2044b3940006fccc1e42","name":"3.5.8 git commit","tags":["patch"]},{"url":"https://github.com/openssl/openssl/commit/9ec2f6d2ae2bcad907cf7ee38584855bafe4979a","name":"3.4.7 git commit","tags":["patch"]},{"url":"https://github.com/openssl/openssl/commit/a0c8ec557d9cac078f032d76cdf684fe743eb382","name":"3.0.22 git commit","tags":["patch"]}],"metrics":[{"format":"other","other":{"content":{"text":"Moderate"},"type":"https://openssl-library.org/policies/general/security-policy/"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-787","description":"CWE-787 Out-of-bounds Write","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"openssl","orgId":"3a12439a-ef3a-4c79-92e6-6081a721f1e5","dateUpdated":"2026-08-25T12:59:34.428Z"},"credits":[{"lang":"en","type":"reporter","value":"Bhabani Sankar Das"},{"lang":"en","type":"reporter","value":"Filipe Casal(Trail of Bits)"},{"lang":"en","type":"remediation developer","value":"Daniel Kubec"}],"datePublic":"2026-08-25T11:36:16.000Z","source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 0.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.5,"attackVector":"NETWORK","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-08-25T14:29:50.344129Z","id":"CVE-2026-63072","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":"2026-08-25T14:29:55.378Z"}}]}}}