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Kernel memory disclosure and denial of service in MikroTik RouterOS btest service

CVSS 4.0 8.8 HIGHCheck source for fixed versionsCISA KEV

cve-program · CVE-2026-67277

Published

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)

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Affected versions, risk and source history

Exploitation and risk

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CVE-2026-67277

Listed in CISA KEV · added 10 Sep 2026 · MikroTik · RouterOS

MikroTik RouterOS contains a missing authentication for critical function vulnerability which allows kernel memory disclosure and denial of service in the btest service.

CISA source · CISA-cited reference

No EPSS score is available here for this CVE.

Saved 23 Oct 2026 16:01:26 UTC · View this risk record (JSON)

cve-program · CVE-2026-67277

Published

Kernel memory disclosure and denial of service in MikroTik RouterOS btest service

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)

Source published
5 Sep 2026 20:00:56 UTC
Source modified
11 Sep 2026 03:55:58 UTC
Saved here
23 Oct 2026 15:48:27 UTC
Source terms
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Original source record · Cite this exact observation · Complete original publisher JSON

Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 4.0 · 8.8 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

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Sources read 15 Nov 01:41 UTC · 255 of 275 readable · 253 fully read · documentation 469/469 current