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CVE-2026-89028

HIGHCVSS 7.5/10EPSS 0.58%

Last modified

CVE-2026-89028 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.. EPSS estimates a 0.58% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS 4.0
8.2/10

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability
0.58%

45.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
MikroTikRouterOS<= 6.49.18; >= 7.0.0, <= 7.11.2

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-89028?
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.
How severe is CVE-2026-89028?
CVE-2026-89028 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.58% probability of exploitation in the next 30 days.
How do I fix CVE-2026-89028?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST