{"apiVersion":"1.0","identifier":"CVE-2026-63073","description":"Issue summary: OpenSSL CMP response validation passed an unexpected response sender distinguished name directly as the format string to `ERR_raise_data()`. Impact summary: A malicious or intercepted CMP endpoint can crash a CMP client that enforces an expected sender or uses a pinned server certificate whose subject becomes the default expected sender. CWE: CWE-134 (Use of Externally-Controlled Format String) Description: When validating a received CMP message, ossl_cmp_msg_check_update() converts the peer-supplied sender distinguished name with X509_NAME_oneline() and passes it directly as the format argument to ERR_raise_data(). Percent characters survive the conversion, so a sender DN such as -CN=%s%n- reaches BIO_vsnprintf() as an attacker-controlled format string with no matching variadic arguments. This path is only reached when the caller configures an expected sender or pins a server certificate, which is the normal configuration for a CMP client validating server responses. Since the attacker controls the format string but none of the variadic arguments, such specifiers as %s and %n dereference or write through unrelated stack contents and crash the client. The reliable consequence is a denial of service, when the response comes from a malicious or intercepted CMP endpoint. There is no controlled memory write, arbitrary-address read, or reliable path to remote code execution. FIPS impact: no No FIPS modules are affected by this issue, as the CMP protocol implementation is outside the OpenSSL FIPS module boundary.","publishedAt":"2026-08-25T13:19:26","lastModifiedAt":"2026-08-25T13:19:26","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-63073","cvssScore":null,"cvssVector":"Pending","epssProbability":0.00409,"riskScore":0,"affectedProduct":"OpenSSL","affectedVersions":"unknown","vulnerabilityType":"Library","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-63073","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-63073","en":"https://www.redsauce.net/en/cves/CVE-2026-63073","fr":"https://www.redsauce.net/fr/cves/CVE-2026-63073","pt":"https://www.redsauce.net/pt/cves/CVE-2026-63073","de":"https://www.redsauce.net/de/cves/CVE-2026-63073","sk":"https://www.redsauce.net/sk/cves/CVE-2026-63073","el":"https://www.redsauce.net/el/cves/CVE-2026-63073"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-63073"}}