CVE-2026-89028: Heap-based Buffer Overflow in MikroTik RouterOS
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.
AI Analysis
Technical Summary
MikroTik RouterOS versions up to 6.49.18 and 7.11.2 are affected by a heap memory corruption vulnerability in the SMB1 SessionSetupAndX handler of the userspace SMB daemon. The flaw arises when a remote attacker sends a malformed SMB1 request with a specially crafted uniPwdLen field that triggers an integer underflow. This underflow results in an incorrect copy length used in a memory copy operation, leading to heap buffer overflow and corruption of adjacent heap memory.
Potential Impact
Successful exploitation can corrupt adjacent heap memory remotely without authentication or user interaction. This may lead to denial of service or potentially enable further exploitation, depending on the memory corruption consequences. The CVSS 4.0 base score is 8.2, indicating a high severity vulnerability with network attack vector, low attack complexity, no privileges required, and no user interaction needed.
Mitigation Recommendations
The vulnerability affects MikroTik RouterOS versions up to 6.49.18 and 7.11.2. A fix is available in RouterOS version 7.24 and later. Users should upgrade to version 7.24 or newer to remediate this issue. No other mitigation guidance is provided or required.
CVE-2026-89028: Heap-based Buffer Overflow in MikroTik RouterOS
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
Score 8.2high
Affected software
MikroTik
RouterOS
pkg:github/mikrotik/routerosRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
MikroTik RouterOS versions up to 6.49.18 and 7.11.2 are affected by a heap memory corruption vulnerability in the SMB1 SessionSetupAndX handler of the userspace SMB daemon. The flaw arises when a remote attacker sends a malformed SMB1 request with a specially crafted uniPwdLen field that triggers an integer underflow. This underflow results in an incorrect copy length used in a memory copy operation, leading to heap buffer overflow and corruption of adjacent heap memory.
Potential Impact
Successful exploitation can corrupt adjacent heap memory remotely without authentication or user interaction. This may lead to denial of service or potentially enable further exploitation, depending on the memory corruption consequences. The CVSS 4.0 base score is 8.2, indicating a high severity vulnerability with network attack vector, low attack complexity, no privileges required, and no user interaction needed.
Mitigation Recommendations
The vulnerability affects MikroTik RouterOS versions up to 6.49.18 and 7.11.2. A fix is available in RouterOS version 7.24 and later. Users should upgrade to version 7.24 or newer to remediate this issue. No other mitigation guidance is provided or required.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-10T16:23:54.472Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6aaa9a6155bf5e2cf5aab8ef
Added to database: 09/16/2026, 13:32:17 UTC
Last enriched: 09/16/2026, 13:46:46 UTC
Last updated: 09/17/2026, 03:22:34 UTC
Views: 11
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.