SSH Pre-Authentication Rekey State Bypass in MikroTik RouterOS
33Vexday Risk Score
No sign of exploitation. It has a public proof of concept.
ssvc Attendcvss 6.9epss 0.4%
exploitation probability
0.4%top 62% of all CVEs
observed exploitation
nono source reports it
1 public exploit(s)
RouterOS SSH enters the connection protocol after a client-requested rekey even though user authentication was never attempted, allowing an unauthenticated client to open a session channel and send an exec request. On affected builds the server dispatches the command, enabling unauthenticated creation, overwrite, and reconstruction of files in the RouterOS managed file namespace, including support files containing configuration and diagnostic data.This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Affected products
Mikrotik · RouterOSpublic PoCs found — 1
cve_referencenpratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/unverified⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
References
https://cert.pl/en/posts/2026/09/mikrotik-routeros-cvehttps://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800https://mikrotik.com/supportsec/september-2026-vulnerability/https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/