Mikrotik RouterOS before 6.42.7 and 6.40.9 is vulnerable to a memory exhaustion vulnerability.

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• mikrotik routerosbefore 6.40.9
• mikrotik routerosbefore 6.42.7

Other highest-scoring records for the same primary product.

• CVE-2018-14847MikroTik RouterOS through 6.42 allows unauthenticated remote attackers to read arbitrary files and remote authenticated attackers to write aKEV
  95Now
• CVE-2018-7445A buffer overflow was found in the MikroTik RouterOS SMB service when processing NetBIOS session request messages.KEV
  87Now
• CVE-2026-86060SSH session privilege manipulation via a crafted username in Mikrotik RouterOSKEV
  67This week
• CVE-2026-67277Kernel memory disclosure and denial of service in MikroTik RouterOS btest serviceKEV
  65This week
• CVE-2026-67279SSH Pre-Authentication Rekey State Bypass in MikroTik RouterOSKEV
  57Plan
• CVE-2017-20149The Mikrotik RouterOS web server allows memory corruption in releases before Stable 6.38.5 and Long-term 6.37.5, aka Chimay-Red.
  40Plan

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1function expand(node) {2  return node.children.map(expand);3}

1const MAX_DEPTH = 32;2function expand(node, depth = 0) {3  if (depth > MAX_DEPTH) throw new Error("too deep");4  return node.children.map((c) => expand(c, depth + 1));5}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.