{"id":"CVE-2026-67277","aliases":["EUVD-2026-72025","GHSA-6q2x-6fhj-r3w8"],"status":"published","title":"Kernel memory disclosure and denial of service in MikroTik RouterOS btest service","description":"RouterOS accepts a \"related\" btest connection before the corresponding primary session has completed authentication. An unauthenticated client can use this state to start an IPv4 UDP test. With \"random-data=false\", the sender transmits an uninitialized tail from a kernel packet buffer. A separate unchecked, inverted packet-size interval causes unsigned integer underflow, anomalously large fragmented output, and can restart the RouterOS kernel.\n\n\n\nThis issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)","severity":{"version":"4.0","score":8.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.0156,"percentile":0.75562,"model":"v2026.06.15"},"facts":{"in_kev":true,"known_exploited":true,"public_exploit":false,"fix_available":false},"cwes":["CWE-306"],"published":"2026-09-05T20:00:56Z","modified":"2026-09-11T15:32:27Z","kev":{"date_added":"2026-09-10","due_date":"2026-09-13","required_action":"Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.","known_ransomware_use":"Unknown"},"exploitation":[{"source":"euvd","since":"2026-09-05"},{"source":"kev","since":"2026-09-10"}],"products":[{"vendor":"mikrotik","product":"routeros"}],"references":[{"url":"https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve","tags":["third-party-advisory","Third Party Advisory"]},{"url":"https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/","tags":["technical-description","Mitigation","Third Party Advisory"]},{"url":"https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/","tags":["exploit","Exploit","Third Party Advisory"]},{"url":"https://mikrotik.com/supportsec/september-2026-vulnerability/","tags":["vendor-advisory","Vendor Advisory"]},{"url":"https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802","tags":["release-notes","Release Notes"]},{"url":"https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801","tags":["release-notes","Release Notes"]},{"url":"https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800","tags":["release-notes","Release Notes"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-67277","tags":["government-resource","US Government Resource"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-67277"},{"url":"https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited"},{"url":"https://mikrotik.com/supportsec/september-2026-vulnerability"},{"url":"https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain"},{"url":"https://github.com/advisories/GHSA-6q2x-6fhj-r3w8"}],"sources":{"cve":[{"id":"CVE-2026-67277","title":"Kernel memory disclosure and denial of service in MikroTik RouterOS btest service","description":"RouterOS accepts a \"related\" btest connection before the corresponding primary session has completed authentication. An unauthenticated client can use this state to start an IPv4 UDP test. With \"random-data=false\", the sender transmits an uninitialized tail from a kernel packet buffer. A separate unchecked, inverted packet-size interval causes unsigned integer underflow, anomalously large fragmented output, and can restart the RouterOS kernel.\n\n\n\nThis issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)","status":"published","published":"2026-09-05T20:00:56.614Z","modified":"2026-09-11T03:55:58.675Z","cvss":[{"version":"4.0","score":8.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T14:20:06.562031Z"}],"euvd":[{"id":"EUVD-2026-72025","description":"RouterOS accepts a \"related\" btest connection before the corresponding primary session has completed authentication. An unauthenticated client can use this state to start an IPv4 UDP test. With \"random-data=false\", the sender transmits an uninitialized tail from a kernel packet buffer. A separate unchecked, inverted packet-size interval causes unsigned integer underflow, anomalously large fragmented output, and can restart the RouterOS kernel.\n\n\n\nThis issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)","status":"published","published":"2026-09-05T20:00:56Z","modified":"2026-09-11T03:55:58Z","cvss":[{"version":"4.0","score":8.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"exploited_since":"2026-09-05","updated_at":"2026-11-02T17:28:23.364345Z"}],"ghsa":[{"id":"GHSA-6q2x-6fhj-r3w8","title":"RouterOS accepts a \"related\" btest connection before the corresponding primary session has...","description":"RouterOS accepts a \"related\" btest connection before the corresponding primary session has completed authentication. An unauthenticated client can use this state to start an IPv4 UDP test. With \"random-data=false\", the sender transmits an uninitialized tail from a kernel packet buffer. A separate unchecked, inverted packet-size interval causes unsigned integer underflow, anomalously large fragmented output, and can restart the RouterOS kernel.\n\n\n\nThis issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)","status":"published","published":"2026-09-05T21:31:19Z","modified":"2026-09-11T15:32:27Z","cvss":[{"version":"4.0","score":8.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"},{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","level":"high"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T15:11:44.427999Z"}],"kev":[{"id":"CVE-2026-67277","title":"MikroTik RouterOS Missing Authentication for Critical Function Vulnerability","description":"MikroTik RouterOS contains a missing authentication for critical function vulnerability which allows kernel memory disclosure and denial of service in the btest service.","cwes":["CWE-306"],"kev":{"date_added":"2026-09-10","due_date":"2026-09-13","required_action":"Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.","known_ransomware_use":"Unknown"},"updated_at":"2026-11-02T17:00:15.999436Z"}],"nvd":[{"id":"CVE-2026-67277","description":"RouterOS accepts a \"related\" btest connection before the corresponding primary session has completed authentication. An unauthenticated client can use this state to start an IPv4 UDP test. With \"random-data=false\", the sender transmits an uninitialized tail from a kernel packet buffer. A separate unchecked, inverted packet-size interval causes unsigned integer underflow, anomalously large fragmented output, and can restart the RouterOS kernel.\n\n\n\nThis issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)","status":"published","published":"2026-09-05T20:17:18.12Z","modified":"2026-09-11T12:52:29.533Z","cvss":[{"version":"4.0","score":8.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","level":"high","assessor":"primary"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T14:12:44.082631Z"}]}}