MikroTik RouterOS < 7.24 Heap Corruption via SMB1 SessionSetupAndX (CVE-2026-89028) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-89028

MikroTik RouterOS < 7.24 Heap Corruption via SMB1 SessionSetupAndX

Answer in brief

CVE-2026-89028 records a Unknown severity vulnerability in MikroTik RouterOS < 7.24 Heap Corruption via SMB1 SessionSetupAndX. The current sources do not mark it as known exploited. The current feed maps MikroTik/RouterOS (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 16, 2026Updated Sep 16, 2026Source checked Sep 17, 2026First seen by HOL Sep 16, 2026Material review Sep 16, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps MikroTik/RouterOS (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
MikroTik/RouterOSgeneric	0 \|\| 7.0.0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for MikroTik/RouterOS.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 16, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.