{"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":"critical","cvss":9.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","cwe":["CWE-347"],"vendor":"mikrotik","product":"routeros","affected":["routeros >= 7.0, < 7.23.6","routeros >= 7.24, < 7.24.3"],"patched":["routeros 7.24.3"],"published":"2026-09-05","updated":"2026-09-25","sourceUpdated":"2026-09-25T14:56:04.743","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","score-dispute"],"epss":0.00261,"epssPercentile":0.17752,"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-08T15:30:45.430794Z"},"scores":{"nvd":9.1,"cna":6.3},"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## Affected\n\n- `routeros >= 7.0, < 7.23.6`\n- `routeros >= 7.24, < 7.24.3`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `routeros 7.24.3`","depth":"abyssal","depthScore":62,"depthScoreParts":{"impact":50.1,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":210878,"id":"CVE-2026-67278","ts":1790349090609,"field":"cvss","old":"6.3","new":"9.1"},{"seq":210877,"id":"CVE-2026-67278","ts":1790349090609,"field":"severity","old":"medium","new":"critical"},{"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"}]}