CVE coverage

CVE-2026-67277

CVSS 8.2 Actively exploited (KEV) no coverage

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. This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)

Detection rules

No detection found — yet

None of Sigma, Elastic, Splunk ESCU, YARA, Microsoft Sentinel, Snort, or Suricata currently has a rule referencing CVE-2026-67277.

This CVE is on CISA's Known Exploited Vulnerabilities list. It is being exploited in the wild with no public detection rule — worth writing one.