CVE-2026-20221mediumCWE-476

CVE-2026-20221: medium-severity vulnerability in Cisco Cyber Vision

Multiple Cisco Products Snort 3 Generic Routing Encapsulation Denial of Service Vulnerabilities

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13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 5.8epss 0.6%
Multiple Cisco products are affected by a vulnerability in the generic routing encapsulation (GRE) tunnel decapsulation feature of the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause an unexpected restart of the Snort 3 Detection Engine. This vulnerability is due to improper handling of nested GRE traffic. An attacker could exploit this vulnerability by sending a crafted GRE payload through an affected device. A successful exploit could allow the attacker to trigger an unexpected reload of the Snort 3 Detection Engine, resulting in either a bypass or denial of service (DoS) condition, depending on device configuration. For more information, see the section of this advisory. The Snort 3 Detection Engine will restart automatically. No manual intervention is required.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
Affected products
Cisco · Cisco Cyber VisionCisco · Cisco Open Source Snort3Cisco · Cisco Secure Firewall Threat Defense (FTD) SoftwareCisco · Cisco Umbrella Insights Virtual ApplianceCisco · Cisco UTD SNORT IPS Engine Software
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