{"id":"CVE-2026-63073","title":"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\nt…","summary":"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\nt…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-134"],"vendor":"openssl","product":"openssl","affected":["openssl >= 3.4.0, < 3.4.7","openssl >= 3.5.0, < 3.5.8","openssl >= 3.6.0, < 3.6.4","openssl >= 4.0.0, < 4.0.2"],"patched":["openssl 4.0.2"],"published":"2026-08-25","updated":"2026-09-11","sourceUpdated":"2026-09-11T21:16:45.633","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-63073","references":[{"url":"https://github.com/openssl/openssl/commit/0cc20b322639919aa423e90799d9a57c3b4b76ca","label":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/6a0acc072b4d37a7cac1252a29c1ce1f00c5ec29","label":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/7eb2e3ec9d1d4f35c8022fccd4b03398b3f33e21","label":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/a7e5a6eea8fd3ccca6b6fbba031a5fbf8a3d93b4","label":"openssl-security@openssl.org"},{"url":"https://openssl-library.org/news/secadv/20260825.txt","label":"openssl-security@openssl.org"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63073.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-63073"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2517565"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-63073"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63073"},{"url":"https://access.redhat.com/errata/RHSA-2026:67154"},{"url":"https://access.redhat.com/errata/RHSA-2026:67165"},{"url":"https://access.redhat.com/errata/RHSA-2026:59641"},{"url":"https://access.redhat.com/errata/RHSA-2026:59635"},{"url":"https://access.redhat.com/errata/RHSA-2026:67956"}],"tags":["nvd","csaf","vex","red-hat","score-dispute"],"epss":0.00929,"epssPercentile":0.59069,"ingestedAt":"2026-09-12T00:03:49.031Z","scores":{"nvd":9.8,"vendor":5.9},"slug":"CVE-2026-63073","body":"## Overview\n\nIssue 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.\n\n## Affected\n\n- `openssl >= 3.4.0, < 3.4.7`\n- `openssl >= 3.5.0, < 3.5.8`\n- `openssl >= 3.6.0, < 3.6.4`\n- `openssl >= 4.0.0, < 4.0.2`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `openssl 4.0.2`\n\n## Vendor advisories\n\n- **RHSA-2026:67154** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10) · released 2026-09-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:67154)\n- **RHSA-2026:67165** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9) · released 2026-09-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:67165)\n- **RHSA-2026:59641** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59641)\n- **RHSA-2026:59635** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59635)\n- **Red Hat VEX** · Low · affected: Red Hat Developer Hub, Red Hat Enterprise Linux 10, Red Hat JBoss Core Services, Red Hat JBoss Web Server 6, Red Hat JBoss Web Server 7, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Developer Hub, Red Hat Enterprise Linux 10, Red Hat JBoss Core Services, Red Hat JBoss Web Server 6, … · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63073.json)\n- **RHSA-2026:67956** · Red Hat · fixed in: Red Hat Update Infrastructure 5 · released 2026-09-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:67956)","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}