Intel

CVE-2026-89028

RouterOS: Heap-based Buffer Overflow (CVE-2026-89028)

highEPSS 0.6%

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.

Source: cvelistv5NVD (NIST)BSI CSAFBSI WID Portal

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

MikroTikRouterOS
< 7.24fixed in 7.24

Metrics

XIEM Effective CVSS
8.2
Source: cna-v4
EPSS percentile
46.1 %
High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status
—
Show all metrics
Severity
high
Priority score
88.02
Exploit maturity
no public PoC known
CVSS v3
7.5
CVSS v4
8.2
EPSS score
0.6 %
Low — model estimates < 1% exploitation likelihood.
Published
2026-09-16 13:12 UTC
CWE
CWE-122, CWE-191

Weakness classes (CWE)

  • CWE-122Variant

    Heap-based Buffer Overflow

    A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

    cwe.mitre.org →

  • CWE-191Base

    Integer Underflow (Wrap or Wraparound)

    The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.

    cwe.mitre.org →

References & sources

Reanalysis & status changes

Chronological NVD audit events for this CVE — reanalyses, CVSS updates, CPE diffs.

  1. CVE Modified2026-09-17 20:18 UTC· 134c704f-9b21-4f2e-91b3-4a467353bcc0
    • SSVC: {"id":"CVE-2026-89028","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalI…
  2. New CVE Received2026-09-16 14:17 UTC· disclosure@vulncheck.com
    • 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 V4.0: 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
    • CVSS V3.1: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
    • CWE: CWE-191