{"id":"CVE-2026-67278","state":"PUBLISHED","title":"TLS server impersonation possible in Mikrotik RouterOS","description":"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 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.","publishedAt":"2026-09-05T20:00:57.258Z","updatedAt":"2026-09-17T14:20:12.715Z","severity":{"score":6.3,"label":"Medium","version":"4.0","vector":"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","source":"CERT-PL"},"assigner":"CERT-PL","products":["Mikrotik RouterOS"],"affected":[{"vendor":"Mikrotik","product":"RouterOS","defaultStatus":"unaffected","versions":[{"version":"7.24","status":"affected","lessThan":"7.24.3","versionType":"custom"},{"version":"7.0.0","status":"affected","lessThan":"7.23.6","versionType":"custom"}]}],"references":["https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve","https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/","https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/","https://mikrotik.com/supportsec/september-2026-vulnerability/","https://forum.mikrotik.com/t/7-23-6-long-term-is-released/273139","https://forum.mikrotik.com/t/7-24-3-stable-is-released/273138"],"weaknesses":["CWE-347"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/67xxx/CVE-2026-67278.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-67278","state":"PUBLISHED","datePublished":"2026-09-05T20:00:57.258Z","dateUpdated":"2026-09-17T14:20:12.715Z","assignerShortName":"CERT-PL","assignerOrgId":"4bb8329e-dd38-46c1-aafb-9bf32bcb93c6","dateReserved":"2026-07-29T11:59:30.538Z"},"containers":{"cna":{"title":"TLS server impersonation possible in Mikrotik RouterOS","descriptions":[{"lang":"en","value":"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 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."}],"affected":[{"vendor":"Mikrotik","product":"RouterOS","defaultStatus":"unaffected","versions":[{"version":"7.24","status":"affected","lessThan":"7.24.3","versionType":"custom"},{"version":"7.0.0","status":"affected","lessThan":"7.23.6","versionType":"custom"}]}],"references":[{"url":"https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve","tags":["third-party-advisory"]},{"url":"https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/","tags":["technical-description"]},{"url":"https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/","tags":["exploit"]},{"url":"https://mikrotik.com/supportsec/september-2026-vulnerability/","tags":["vendor-advisory"]},{"url":"https://forum.mikrotik.com/t/7-23-6-long-term-is-released/273139","tags":["release-notes"]},{"url":"https://forum.mikrotik.com/t/7-24-3-stable-is-released/273138","tags":["release-notes"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","subConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","subIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"MEDIUM","baseScore":6.3,"vectorString":"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"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-347","lang":"en","description":"CWE-347 Improper verification of cryptographic signature","type":"CWE"}]}],"providerMetadata":{"shortName":"CERT-PL","orgId":"4bb8329e-dd38-46c1-aafb-9bf32bcb93c6","dateUpdated":"2026-09-17T14:20:12.715Z"},"datePublic":"2026-09-05T00:00:00.000Z","cpeApplicability":[{"operator":"OR","nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:mikrotik:routeros:*:*:*:*:*:*:*:*","versionStartIncluding":"7.24","versionEndExcluding":"7.24.3"},{"vulnerable":true,"criteria":"cpe:2.3:a:mikrotik:routeros:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0.0","versionEndExcluding":"7.23.6"}]}]}],"credits":[{"lang":"en","value":"Sławomir Rozbicki (CERT.PL)","type":"finder"},{"lang":"en","value":"Robert Żegleń","type":"finder"}],"source":{"discovery":"INTERNAL"},"x_generator":{"engine":"Vulnogram 1.0.3"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-08T15:30:45.430794Z","id":"CVE-2026-67278","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-08T15:30:53.723Z"}}]}}}