# CVE-2026-67643: Microsoft SQL Server heap-based buffer overflow

Source: https://junglewise.ai/threats/cve-2026-67643-microsoft-sql-server-heap-based-buffer-overflow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-08. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-67643 · Severity: critical · CVSS 9.8 · Published 2026-09-08

SQL Server is Microsoft's relational database system used to store and manage critical business data across organizations. A heap-based buffer overflow vulnerability allows an attacker on the network to execute arbitrary code on the affected server without authentication, potentially leading to complete compromise of the database, theft of sensitive data, and disruption of business operations.

Technologies: [Microsoft SQL Server](https://junglewise.ai/threats/technologies/sql-server). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-67643 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-67643 being exploited in the wild.

**How severe is CVE-2026-67643?** Critical severity, with a CVSS score of 9.8, published 8 September 2026.

**Which products and versions are affected?** Microsoft SQL Server.

**Is there a fix for CVE-2026-67643?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-67643 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-67643?** Check whether you run Microsoft SQL Server. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A heap-based buffer overflow vulnerability exists in Microsoft SQL Server that can be exploited by an unauthenticated attacker over the network. The vulnerability results from improper memory bounds checking in the database engine, allowing an attacker to write beyond allocated heap memory and overwrite adjacent objects. This can be leveraged to achieve remote code execution with the privileges of the SQL Server service. The attack requires network access to the SQL Server port but does not require prior authentication or user interaction. Microsoft has released security updates to address this issue.

## Affected products

- Microsoft SQL Server

## Timeline

- 2026-09-08: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-67643](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-67643)

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