High severity · published Sep 16, 2026
CVE-2026-89028
MikroTik RouterOS < 7.24 Heap Corruption via SMB1 SessionSetupAndX
7.5
CVSS
0.6%
EPSS
No
On KEV
Description
MikroTik RouterOS before 7.24 contains a heap memory corruption vulnerability in the userspace SMB daemon that allows remote attackers to corrupt adjacent heap memory by supplying a crafted uniPwdLen value in the SMB1 SessionSetupAndX handler. An attacker can send a malformed SMB1 request with a uniPwdLen field that triggers an integer underflow, causing the resulting value to be used as the copy length in a memory copy operation into a smaller heap buffer, corrupting adjacent heap memory.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 48% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RO
RouterOS · MikroTik
through 6.49.18; 7.0.0 through 7.11.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-89028
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-89028
vendor-advisory
https://forum.mikrotik.com/t/7-24-stable-is-released/272381
third-party-advisory
https://www.vulncheck.com/advisories/mikrotik-routeros-heap-corruption-via-smb1-sessionsetupandx
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