# CVE-2026-20005: Cisco Snort 3 Detection Engine denial of service in SSL handshake parsing

Source: https://junglewise.ai/threats/cve-2026-20005-cisco-snort-3-detection-engine-denial-of-service-in-ssl-handshake  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-04. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-20005 · Severity: medium · CVSS 5.8 · Published 2026-03-04

Snort 3 is a network intrusion detection and prevention engine deployed across multiple Cisco security products including firewalls, threat defense systems, and routers. A flaw in SSL handshake packet parsing allows unauthenticated remote attackers to send specially crafted packets that crash the detection engine, temporarily disrupting packet inspection and creating a window for malicious traffic to bypass security monitoring.

Technologies: [Cisco Cyber Vision](https://junglewise.ai/threats/technologies/cyber-vision), [Cisco IOS XE Software](https://junglewise.ai/threats/technologies/ios-xe-software), [Cisco Meraki MX Series](https://junglewise.ai/threats/technologies/meraki-mx-series), [Cisco Secure Firewall Threat Defense](https://junglewise.ai/threats/technologies/firepower-threat-defense), [Cisco Snort 3](https://junglewise.ai/threats/technologies/snort-3). Vendors: [Cisco](https://junglewise.ai/threats/vendors/cisco).

## Quick answers

**Is CVE-2026-20005 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-20005 being exploited in the wild.

**How severe is CVE-2026-20005?** Medium severity, with a CVSS score of 5.8, published 4 March 2026.

**Which products and versions are affected?** Cisco Cyber Vision Multiple releases; Cisco IOS XE Software Multiple releases with UTD Snort IPS Engine enabled; Cisco Meraki MX Series Multiple MX models running vulnerable Meraki Software; Cisco Secure Firewall Threat Defense Multiple releases with Snort 3 configured; and 1 more.

**Is there a fix for CVE-2026-20005?** 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-2026-20005 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-20005?** Check whether you run Cisco Cyber Vision, Cisco IOS XE Software, Cisco Meraki MX Series or one of the others listed 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

This vulnerability stems from incomplete parsing of SSL handshake ingress packets in the Snort 3 Detection Engine (CWE-248, CWE-392, CWE-400, CWE-667, CWE-787). An unauthenticated remote attacker can exploit this via network-level access by sending crafted SSL/TLS handshake packets. When processed by the vulnerable engine, these packets trigger an unexpected restart of Snort 3, causing a temporary denial of service and interruption of packet inspection capabilities. No authentication or user interaction is required. Cisco has released software updates addressing these vulnerabilities; no workarounds are available.

## Affected products

- Cisco Snort 3 Multiple versions; see fixed software section
- Cisco Secure Firewall Threat Defense Multiple releases with Snort 3 configured
- Cisco IOS XE Software Multiple releases with UTD Snort IPS Engine enabled
- Cisco Meraki MX Series Multiple MX models running vulnerable Meraki Software
- Cisco Cyber Vision Multiple releases

## Timeline

- 2026-03-04: disclosed: CVE-2026-20005 published; multiple related CVEs (CVE-2026-20065, CVE-2026-20066, CVE-2026-20067, CVE-2026-20068) also disclosed

## References

- [https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-multi-dos-XFWkWSwz](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-multi-dos-XFWkWSwz)

## Related threats

- [Cisco Snort 3 memory management denial of service](https://junglewise.ai/threats/cve-2026-76489-multiple-cisco-products-are-affected-by-a-vulnerability-in-the)
- [Cisco Snort 3 Detection Engine denial of service in GTP codec](https://junglewise.ai/threats/cve-2026-76445-multiple-cisco-products-are-affected-by-a-vulnerability-in-the)
- [Cisco Snort 3 uncontrolled resource consumption](https://junglewise.ai/threats/cve-2026-20356-as-part-of-cisco-s-ongoing-commitment-to-proactive-security-and)
- [Cisco Snort 3 improper privilege management](https://junglewise.ai/threats/cve-2026-20291-as-part-of-cisco-s-ongoing-commitment-to-proactive-security-and)
- [Cisco Snort 3 incorrect calculation vulnerability](https://junglewise.ai/threats/cve-2026-20236-as-part-of-cisco-s-ongoing-commitment-to-proactive-security-and)