{"attribution":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","cve":{"id":"CVE-2026-63073","sourceIdentifier":"openssl-security@openssl.org","published":"2026-08-25T13:19:26.147","lastModified":"2026-09-11T21:16:45.633","vulnStatus":"Analyzed","cveTags":[],"descriptions":[{"lang":"en","value":"Issue summary: OpenSSL CMP response validation passed an unexpected response\nsender distinguished name directly as the format string to `ERR_raise_data()`.\n\nImpact summary: A malicious or intercepted CMP endpoint can crash a CMP client\nthat enforces an expected sender or uses a pinned server certificate whose\nsubject becomes the default expected sender.\n\nCWE: CWE-134 (Use of Externally-Controlled Format String)\n\nDescription: When validating a received CMP message, ossl_cmp_msg_check_update()\nconverts the peer-supplied sender distinguished name with X509_NAME_oneline()\nand passes it directly as the format argument to ERR_raise_data(). Percent\ncharacters survive the conversion, so a sender DN such as \"CN=%s%n\" reaches\nBIO_vsnprintf() as an attacker-controlled format string with no matching variadic\narguments. This path is only reached when the caller configures an expected\nsender or pins a server certificate, which is the normal configuration for a\nCMP client validating server responses.\n\nSince the attacker controls the format string but none of the variadic\narguments, such specifiers as %s and %n dereference or write through unrelated\nstack contents and crash the client. The reliable consequence is a denial of\nservice, when the response comes from a malicious or intercepted CMP endpoint.\nThere is no controlled memory write, arbitrary-address read, or reliable path\nto remote code execution.\n\nFIPS impact: no\n\nNo FIPS modules are affected by this issue, as the CMP protocol\nimplementation is outside the OpenSSL FIPS module boundary."}],"affected":[{"source":"openssl-security@openssl.org","affectedData":[{"vendor":"OpenSSL","product":"OpenSSL","defaultStatus":"unaffected","versions":[{"version":"4.0.0","lessThan":"4.0.2","versionType":"semver","status":"affected"},{"version":"3.6.0","lessThan":"3.6.4","versionType":"semver","status":"affected"},{"version":"3.5.0","lessThan":"3.5.8","versionType":"semver","status":"affected"},{"version":"3.4.0","lessThan":"3.4.7","versionType":"semver","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-08-31T19:12:48.434586Z","id":"CVE-2026-63073","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"openssl-security@openssl.org","type":"Secondary","description":[{"lang":"en","value":"CWE-134"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*","versionStartIncluding":"3.4.0","versionEndExcluding":"3.4.7","matchCriteriaId":"216D6529-561A-4684-A886-50954FBEBFB2"},{"vulnerable":true,"criteria":"cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*","versionStartIncluding":"3.5.0","versionEndExcluding":"3.5.8","matchCriteriaId":"C5BB9E95-09B6-4163-B51C-D62B528A04DA"},{"vulnerable":true,"criteria":"cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*","versionStartIncluding":"3.6.0","versionEndExcluding":"3.6.4","matchCriteriaId":"B1416826-F2F1-4EA8-9FB2-A56B0DA923C1"},{"vulnerable":true,"criteria":"cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0.0","versionEndExcluding":"4.0.2","matchCriteriaId":"63B8F45B-E44F-481C-815D-AF9CA89C48F6"}]}]}],"references":[{"url":"https://github.com/openssl/openssl/commit/0cc20b322639919aa423e90799d9a57c3b4b76ca","source":"openssl-security@openssl.org","tags":["Patch"]},{"url":"https://github.com/openssl/openssl/commit/6a0acc072b4d37a7cac1252a29c1ce1f00c5ec29","source":"openssl-security@openssl.org","tags":["Patch"]},{"url":"https://github.com/openssl/openssl/commit/7eb2e3ec9d1d4f35c8022fccd4b03398b3f33e21","source":"openssl-security@openssl.org","tags":["Patch"]},{"url":"https://github.com/openssl/openssl/commit/a7e5a6eea8fd3ccca6b6fbba031a5fbf8a3d93b4","source":"openssl-security@openssl.org","tags":["Patch"]},{"url":"https://openssl-library.org/news/secadv/20260825.txt","source":"openssl-security@openssl.org","tags":["Vendor Advisory"]}]}}