{"id":"CVE-2026-67278","title":"MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across RSA-based services, including TLS/X.509 certificate validation and SSH host-key authentication","summary":"MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across RSA-based services, including TLS/X.509 certificate validation and SSH host-key authentication. Because its trust store includes an e=3 root CA, an attacker controllin…","severity":"medium","cvss":6.3,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","cwe":["CWE-347"],"vendor":"Mikrotik","product":"RouterOS","affected":["RouterOS >= 7.24 < 7.24.3","RouterOS >= 7.0.0 < 7.23.6"],"published":"2026-09-05","updated":"2026-09-17","sourceUpdated":"2026-09-17T15:16:50.947","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-67278","references":[{"url":"https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve","label":"cvd@cert.pl"},{"url":"https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/","label":"cvd@cert.pl"},{"url":"https://forum.mikrotik.com/t/7-23-6-long-term-is-released/273139","label":"cvd@cert.pl"},{"url":"https://forum.mikrotik.com/t/7-24-3-stable-is-released/273138","label":"cvd@cert.pl"},{"url":"https://mikrotik.com/supportsec/september-2026-vulnerability/","label":"cvd@cert.pl"},{"url":"https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/","label":"cvd@cert.pl"},{"url":"https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801","label":"cvd@cert.pl"},{"url":"https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800","label":"cvd@cert.pl"},{"url":"https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802","label":"cvd@cert.pl"}],"tags":["nvd","cve.org","exploit-available"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-08T15:30:45.430794Z"},"cvssSource":"cna","epss":0.0018,"epssPercentile":0.07868,"ingestedAt":"2026-09-06T10:53:52.423Z","slug":"CVE-2026-67278","body":"## Overview\n\nMikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across RSA-based services, including TLS/X.509 certificate validation and SSH host-key authentication. Because its trust store includes an e=3 root CA, an attacker controlling or redirecting an outbound RouterOS TLS connection can use the root’s public certificate - without its private key - to forge a trusted intermediate and issue certificates for arbitrary hostnames, enabling TLS server impersonation. The same permissive verification also undermines RSA-based SSH authentication.\n\n\n\nThis issue affects only 7.x branch was fixed in versions: 7.23.6 (Long-term) and 7.24.3 (Stable).\nReleases 7.23.4 and 7.24.2 included an incomplete fix.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":47,"depthScoreParts":{"impact":34.7,"likelihood":0,"exploitation":12,"ransomware":0},"changes":[{"seq":5421,"id":"CVE-2026-67278","ts":1788887281446,"field":"exploit_available","old":"false","new":"true"},{"seq":5420,"id":"CVE-2026-67278","ts":1788887281446,"field":"cvss","old":null,"new":"6.3"},{"seq":5419,"id":"CVE-2026-67278","ts":1788887281446,"field":"severity","old":"none","new":"medium"},{"seq":4304,"id":"CVE-2026-67278","ts":1788886395299,"field":"exploit_available","old":"true","new":"false"},{"seq":4303,"id":"CVE-2026-67278","ts":1788886395299,"field":"cvss","old":"6.3","new":null},{"seq":4302,"id":"CVE-2026-67278","ts":1788886395299,"field":"severity","old":"medium","new":"none"},{"seq":3276,"id":"CVE-2026-67278","ts":1788885294101,"field":"exploit_available","old":"false","new":"true"},{"seq":3275,"id":"CVE-2026-67278","ts":1788885294101,"field":"cvss","old":null,"new":"6.3"},{"seq":3274,"id":"CVE-2026-67278","ts":1788885294101,"field":"severity","old":"none","new":"medium"}]}