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CVE-2026-67277— Kernel memory disclosure and denial of service in MikroTik RouterOS btest service

Quick assessment

Affected
Mikrotik RouterOS
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

RouterOS 在对应的主会话完成认证之前，就接受了“关联”的 btest 连接。未认证的客户机可以利用这一状态发起 IPv4 UDP 测试。当设置 时，发送方会传输来自内核数据包缓冲区的未初始化尾部数据。另一个未被检查的、倒置的数据包大小区间会导致无符号整数下溢，产生异常大的分片输出，并可能重启 RouterOS 内核。 该问题已在以下版本中修复：6.49.21（长期支持版）、7.23.4（长期支持版）和 7.24.2（稳定版）。

CVSS 8.8 · High EPSS 0.43% · P37

Affected Version Matrix 3

VendorProduct Version RangeStatus
Mikrotik RouterOS 7.24< 7.24.2 affected
7.0.0< 7.23.4 affected
6.0.0< 6.49.21 affected
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I. Basic Information for CVE-2026-67277

Vulnerability Information
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Vulnerability Title
Kernel memory disclosure and denial of service in MikroTik RouterOS btest service
Source: CVE Program / CVE List V5
Vulnerability 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. This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
关键功能的认证机制缺失
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Mikrotik RouterOS 7.24 ~ 7.24.2 -

II. Public POCs for CVE-2026-67277

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III. Intelligence Information for CVE-2026-67277

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Security Blog Posts for CVE-2026-67277 (3)

Vendor Pages for CVE-2026-67277 (4)

Same Patch Batch · Mikrotik · 2026-09-05 · 6 CVEs total

CVE-2026-86060 9.2 CRITICAL SSH session privilege manipulation via a crafted username in Mikrotik RouterOS
CVE-2026-67276 9.2 CRITICAL SSH user impersonation possible in Mikrotik RouterOS
CVE-2026-67281 8.7 HIGH Unauthenticated file read in Mikrotik RouterOS
CVE-2026-67279 6.9 MEDIUM SSH Pre-Authentication Rekey State Bypass in MikroTik RouterOS
CVE-2026-67278 6.3 MEDIUM TLS server impersonation possible in Mikrotik RouterOS

IV. Related Vulnerabilities

Same product: RouterOS
Same vendor: Mikrotik
Same weakness: CWE-306

V. Comments for CVE-2026-67277

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