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CVE-2026-20221

CVE-2026-20221 · Multiple Cisco Products Snort 3 Generic Routing Encapsulation Denial of Service Vulnerabilities

This page contains facts from public vulnerability sources. Check the original advisory before updating.

This page shows selected source facts. See the linked advisories for the complete description and affected versions.

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 5.8 · Medium · EPSS 0.5%

Published
Updated

Affected products and versions

  • cisco cyber vision

    Versions
    • 3.0.0: Affected
    • 3.0.2: Affected
    • 3.0.3: Affected
    • 3.0.1: Affected
    • 3.1.0: Affected
    • 3.0.4: Affected
    • 3.1.1: Affected
    • 3.1.2: Affected
    • 3.2.0: Affected
    • 3.0.5: Affected
    • 3.2.1: Affected
    • 3.0.6: Affected
    • 3.2.2: Affected
    • 3.2.3: Affected
    • 3.2.4: Affected
    • 4.0.0: Affected
    • 4.0.1: Affected
    • 4.0.2: Affected
    • 4.0.3: Affected
    • 4.1.0: Affected
    • 4.1.1: Affected
    • 4.1.2: Affected
    • 4.1.3: Affected
    • 4.1.4: Affected
    • 4.2.0: Affected
    • 4.2.1: Affected
    • 4.1.5: Affected
    • 4.2.2: Affected
    • 4.2.X: Affected
    • 4.2.3: Affected
    • 4.2.4: Affected
    • 4.2.6: Affected
    • 4.1.6: Affected
    • 4.3.0: Affected
    • 4.3.1: Affected
    • 4.3.2: Affected
    • 4.3.3: Affected
    • 4.4.0: Affected
    • 4.4.1: Affected
    • 4.4.2: Affected
    • 4.4.3: Affected
    • 4.1.7: Affected
    • 5.0.0: Affected
    • 5.0.1: Affected
    • 5.0.2: Affected
    • 5.1.0: Affected
    • 5.1.1: Affected
    • 5.1.2: Affected
    • 5.1.3: Affected
    • 5.2.0: Affected
    • 5.2.1: Affected
    • 5.3.0: Affected
    • 5.3.1: Affected
    • 5.3.2: Affected
    • 5.3.3: Affected
    • 5.5.1: Affected
    • 5.6.1: Affected
    • 5.6.0: Affected
    • 5.4.0: Affected
    • 5.4.1: Affected
    • 5.4.2: Affected

    No fix published

  • cisco open source snort3

    Versions
    • 3.12.2.0: Affected
    • 3.1.2.0: Affected
    • 3.1.3.0: Affected
    • 3.1.4.0: Affected
    • 3.1.5.0: Affected
    • 3.1.6.0: Affected
    • 3.1.7.0: Affected
    • 3.1.8.0: Affected
    • 3.1.9.0: Affected
    • 3.1.10.0: Affected
    • 3.1.12.0: Affected
    • 3.1.13.0: Affected
    • 3.1.14.0: Affected
    • 3.1.15.0: Affected
    • 3.1.16.0: Affected
    • 3.1.17.0: Affected
    • 3.1.18.0: Affected
    • 3.1.19.0: Affected
    • 3.1.20.0: Affected
    • 3.1.21.0: Affected
    • 3.1.22.0: Affected
    • 3.1.23.0: Affected
    • 3.1.24.0: Affected
    • 3.1.25.0: Affected
    • 3.1.27.0: Affected
    • 3.1.28.0: Affected
    • 3.1.29.0: Affected
    • 3.1.30.0: Affected
    • 3.1.31.0: Affected
    • 3.1.32.0: Affected
    • 3.1.36.0: Affected
    • 3.1.38.0: Affected
    • 3.1.39.0: Affected
    • 3.1.40.0: Affected
    • 3.1.41.0: Affected
    • 3.1.42.0: Affected
    • 3.1.43.0: Affected
    • 3.1.45.0: Affected
    • 3.1.47.0: Affected
    • 3.1.48.0: Affected
    • 3.1.50.0: Affected
    • 3.1.51.0: Affected
    • 3.1.52.0: Affected
    • 3.1.53.0: Affected
    • 3.1.55.0: Affected
    • 3.1.56.0: Affected
    • 3.1.57.0: Affected
    • 3.1.58.0: Affected
    • 3.1.59.0: Affected
    • 3.1.60.0: Affected
    • 3.1.61.0: Affected
    • 3.1.62.0: Affected
    • 3.1.63.0: Affected
    • 3.1.64.0: Affected
    • 3.1.65.0: Affected
    • 3.1.66.0: Affected
    • 3.1.67.0: Affected
    • 3.1.69.0: Affected
    • 3.1.70.0: Affected
    • 3.1.71.0: Affected
    • 3.1.72.0: Affected
    • 3.1.73.0: Affected
    • 3.1.74.0: Affected
    • 3.1.75.0: Affected
    • 3.1.76.0: Affected
    • 3.1.77.0: Affected
    • 3.1.78.0: Affected
    • 3.1.81.0: Affected
    • 3.1.82.0: Affected
    • 3.1.83.0: Affected
    • 3.1.84.0: Affected
    • 3.2.1.0: Affected
    • 3.2.2.0: Affected
    • 3.3.0.0: Affected
    • 3.3.1.0: Affected
    • 3.3.2.0: Affected
    • 3.3.3.0: Affected
    • 3.3.4.0: Affected
    • 3.3.5.0: Affected
    • 3.3.7.0: Affected
    • 3.5.0.0: Affected
    • 3.5.1.0: Affected
    • 3.8.1.0: Affected
    • 3.6.0.0: Affected
    • 3.6.2.0: Affected
    • 3.9.3.0: Affected
    • 3.7.2.0: Affected
    • 3.7.0.0: Affected
    • 3.9.6.0: Affected
    • 3.10.0.0: Affected
    • 3.10.2.0: Affected
    • 3.7.4.0: Affected
    • 3.9.0.0: Affected
    • 3.5.2.0: Affected
    • 3.12.1.0: Affected
    • 3.6.1.0: Affected
    • 3.9.2.0: Affected
    • 3.6.3.0: Affected

    No fix published

  • cisco secure firewall threat defense (ftd) software

    Versions
    • 7.0.0: Affected
    • 7.0.0.1: Affected
    • 7.0.1: Affected
    • 7.0.1.1: Affected
    • 7.0.2: Affected
    • 7.2.0: Affected
    • 7.0.2.1: Affected
    • 7.0.3: Affected
    • 7.2.0.1: Affected
    • 7.0.4: Affected
    • 7.2.1: Affected
    • 7.0.5: Affected
    • 7.3.0: Affected
    • 7.2.2: Affected
    • 7.2.3: Affected
    • 7.3.1: Affected
    • 7.2.4: Affected
    • 7.0.6: Affected
    • 7.2.5: Affected
    • 7.2.4.1: Affected
    • 7.3.1.1: Affected
    • 7.4.0: Affected
    • 7.0.6.1: Affected
    • 7.2.5.1: Affected
    • 7.4.1: Affected
    • 7.2.6: Affected
    • 7.0.6.2: Affected
    • 7.4.1.1: Affected
    • 7.2.7: Affected
    • 7.2.5.2: Affected
    • 7.3.1.2: Affected
    • 7.2.8: Affected
    • 7.6.0: Affected
    • 7.4.2: Affected
    • 7.2.8.1: Affected
    • 7.0.6.3: Affected
    • 7.4.2.1: Affected
    • 7.2.9: Affected
    • 7.0.7: Affected
    • 7.7.0: Affected
    • 7.4.2.2: Affected
    • 7.2.10: Affected
    • 7.6.1: Affected
    • 7.4.2.3: Affected
    • 7.0.8: Affected
    • 7.6.2: Affected
    • 7.7.10: Affected
    • 7.7.11: Affected
    • 7.0.8.1: Affected
    • 7.6.2.1: Affected
    • 7.7.10.1: Affected
    • 7.4.2.4: Affected
    • 7.2.10.2: Affected
    • 7.4.3: Affected
    • 7.6.4: Affected
    • 10.0.0: Affected
    • 7.4.4: Affected
    • 7.0.9: Affected
    • 7.2.11: Affected
    • 7.4.7: Affected

    No fix published

  • cisco umbrella insights virtual appliance

    Versions
    • 2.6.0: Affected
    • 2.5.6: Affected
    • 2.5: Affected
    • 2.4.12: Affected
    • 2.7: Affected
    • 2.6.2: Affected
    • 2.5.5: Affected
    • 2.5.4: Affected
    • 2.8: Affected
    • 2.6.1: Affected
    • 2.5.7: Affected
    • 1.5.4: Affected
    • 1.5.5: Affected
    • 1.5.6: Affected
    • 2.0.0: Affected
    • 2.0.2: Affected
    • 2.0.3: Affected
    • 2.1.0: Affected
    • 2.1.2: Affected
    • 2.1.4: Affected
    • 2.1.5: Affected
    • 2.2: Affected
    • 2.2.1: Affected
    • 2.3: Affected
    • 2.3.1: Affected
    • 2.4: Affected
    • 2.4.4: Affected
    • 2.4.6: Affected
    • 2.8.9: Affected
    • 3.0: Affected
    • 3.1: Affected
    • 3.2: Affected
    • 2.8.1: Affected
    • 2.8.2: Affected
    • 2.8.3: Affected
    • 2.8.4: Affected
    • 2.8.5: Affected
    • 3.0.1: Affected
    • 3.0.2: Affected
    • 3.0.4: Affected
    • 3.0.5: Affected
    • 3.1.1: Affected
    • 3.1.2: Affected
    • 3.1.3: Affected
    • 3.1.4: Affected
    • 3.2.1: Affected
    • 3.2.2: Affected
    • 3.2.3: Affected
    • 3.3: Affected
    • 3.3.1: Affected
    • 3.3.2: Affected
    • 3.3.3: Affected
    • 3.3.4: Affected
    • 3.4: Affected
    • 3.4.1: Affected
    • 3.4.2: Affected
    • 3.4.3: Affected
    • 3.4.4: Affected
    • 3.4.5: Affected
    • 3.4.6: Affected
    • 3.5: Affected
    • 2.7.1: Affected
    • 2.7.2: Affected
    • 2.7.6: Affected
    • 2.7.9: Affected
    • 2.7.10: Affected
    • 3.5.1: Affected
    • 3.5.2: Affected
    • 3.6.1: Affected
    • 3.6.2: Affected
    • 3.7: Affected
    • 3.7.1: Affected
    • 3.8.3: Affected

    No fix published

  • cisco utd snort ips engine software

    Versions
    • 3.17.1S: Affected
    • 16.12.3: Affected
    • Fuji-16.9.5: Affected
    • 16.12.4: Affected
    • 17.3.1a: Affected
    • 16.6.6: Affected
    • 16.12.2: Affected
    • Fuji-16.9.6: Affected
    • 3.17.0S: Affected
    • Fuji-16.9.3: Affected
    • Denali-16.3.7: Affected
    • Fuji-16.9.2: Affected
    • Fuji-16.9.4: Affected
    • Everest-16.6.4: Affected
    • Everest-16.6.3: Affected
    • 16.6.5: Affected
    • Denali-16.3.5: Affected
    • 17.2.1r: Affected
    • 17.1.1: Affected
    • Everest-16.6.2: Affected
    • 16.6.7a: Affected
    • Denali-16.3.4: Affected
    • 16.6.1: Affected
    • Denali-16.3.9: Affected
    • Denali-16.3.3: Affected
    • 16.12.1a: Affected
    • 17.3.2: Affected
    • 17.4.1a: Affected
    • 16.12.5: Affected
    • 17.5.1: Affected
    • Fuji-16.9.7: Affected
    • 16.6.9: Affected
    • 17.3.3: Affected
    • 17.5.1a: Affected
    • 17.3.4: Affected
    • 17.3.4a: Affected
    • 17.4.2: Affected
    • 17.4.1b: Affected
    • 17.6.1a: Affected
    • 16.6.10: Affected
    • 17.7.1a: Affected
    • 16.12.6: Affected
    • Fuji-16.9.8: Affected
    • 17.6.2: Affected
    • 17.8.1a: Affected
    • 16.12.7: Affected
    • 17.3.5: Affected
    • 17.6.3: Affected
    • 17.6.3a: Affected
    • 17.7.2: Affected
    • 17.9.1a: Affected
    • 17.6.4: Affected
    • 17.10.1a: Affected
    • 17.3.6: Affected
    • 16.12.8: Affected
    • 17.3.7: Affected
    • 17.9.2a: Affected
    • 17.6.5: Affected
    • 17.11.1a: Affected
    • 17.9.3a: Affected
    • 17.12.1a: Affected
    • 17.9.4: Affected
    • 17.6.6: Affected
    • 17.3.8: Affected
    • 17.3.8a: Affected
    • 17.6.6a: Affected
    • 17.9.4a: Affected
    • 17.12.2: Affected
    • 17.13.1a: Affected
    • 17.9.5a: Affected
    • 17.12.3: Affected
    • 17.6.7: Affected
    • 17.14.1a: Affected
    • 17.12.4: Affected
    • 17.12.3a: Affected
    • 17.15.1a: Affected
    • 17.6.8: Affected
    • 17.9.6: Affected
    • 17.6.8a: Affected
    • 17.16.1a: Affected
    • 17.9.5e: Affected
    • 17.12.4a: Affected
    • 17.15.2c: Affected
    • 17.9.5f: Affected
    • 17.12.4b: Affected
    • 17.15.2a: Affected
    • 17.12.5: Affected
    • 17.17.1: Affected
    • 17.12.5a: Affected
    • 17.9.7a: Affected
    • 17.15.3a: Affected
    • 17.15.3: Affected
    • 17.12.5b: Affected
    • 17.12.5c: Affected
    • 17.15.4: Affected
    • 17.9.7b: Affected
    • 17.18.1: Affected
    • 17.18.1a: Affected

    No fix published

Original sources

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