{"id":"DEBIAN-CVE-2026-63073","details":"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.","modified":"2026-09-13T16:00:07.835505368Z","published":"2026-08-25T13:19:26.147Z","upstream":["CVE-2026-63073"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-63073"}],"affected":[{"package":{"name":"openssl","ecosystem":"Debian:13","purl":"pkg:deb/debian/openssl?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.5.7-1~deb13u2"}]}],"versions":["3.5.1-1","3.5.1-1+deb13u1","3.5.2-1","3.5.3-1","3.5.4-1","3.5.4-1~deb13u1","3.5.4-1~deb13u2","3.5.5-1","3.5.5-1~deb13u1","3.5.5-1~deb13u2","3.5.6-1~deb13u1","3.5.6-1~deb13u2","3.5.7-1~deb13u1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-63073.json"}},{"package":{"name":"openssl","ecosystem":"Debian:14","purl":"pkg:deb/debian/openssl?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.4-1"}]}],"versions":["3.5.1-1","3.5.2-1","3.5.3-1","3.5.4-1","3.5.4-1~deb13u1","3.5.4-1~deb13u2","3.5.5-1","3.5.5-1~deb13u1","3.5.5-1~deb13u2","3.5.6-1~deb13u1","3.5.6-1~deb13u2","3.5.7-1~deb13u1","3.5.7-1~deb13u2","3.6.0-1","3.6.0-2","3.6.0~~alpha1-1","3.6.0~~beta1-1","3.6.1-1","3.6.1-2","3.6.1-3","3.6.2-1","3.6.3-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-63073.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}