Cisco Snort OLE VBA Decompression Stack-based Buffer Overflow Remote Code Execution Vulnerability

October 22nd, 2026
ZDI-26-788 ZDI-CAN-31369

CVE ID

CVE-2026-20218

CVSS Score

8.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors

Cisco

Affected Products

Snort

Vulnerability Details

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Cisco Snort. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the decompression of VBA data in OLE file streams. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of the service account.

Additional Details

Cisco has issued an update to correct this vulnerability. More details can be found at:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-vba-bufdos-jAuFdvn9

Disclosure Timeline

  • 2026-06-30 - Vulnerability reported to vendor
  • 2026-10-22 - Coordinated public release of advisory
  • 2026-10-22 - Advisory Updated

Credit

@TristanInSec

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