# CVE-2026-69639: Windows Libarchive heap-based buffer overflow

Source: https://junglewise.ai/threats/cve-2026-69639-heap-based-buffer-overflow-in-windows-libarchive-allows-an  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-69639 · Severity: critical · CVSS 9.8 · Published 2026-10-13

Libarchive, a library used to handle compressed archive files, contains a heap-based buffer overflow vulnerability in Windows systems. An attacker can exploit this flaw remotely by sending a specially crafted archive file, potentially allowing them to execute arbitrary code and gain complete control of the affected system.

## Quick answers

**Is CVE-2026-69639 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-69639 being exploited in the wild.

**How severe is CVE-2026-69639?** Critical severity, with a CVSS score of 9.8, published 13 October 2026.

**Which products and versions are affected?** Libarchive <UNKNOWN>.

**Is there a fix for CVE-2026-69639?** 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-2026-69639 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-69639?** Check whether you run Libarchive at an affected version. 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 exists in Libarchive's archive processing code on Windows platforms, reachable via network-supplied archive files without authentication or user interaction required. An attacker can craft a malicious archive to overflow heap memory, achieving arbitrary code execution with the privileges of the application using Libarchive.

## Affected products

- Libarchive <UNKNOWN>

## Timeline

- 2026-10-13: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69639](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69639)

## Related threats

- [libarchive heap-based buffer overflow in Windows](https://junglewise.ai/threats/cve-2026-69985-heap-based-buffer-overflow-in-windows-libarchive-allows-an)