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TI-2026-78816 Aliases CVE-2026-20179GHSA-9v2c-x8g8-r7m4

Denial of service in Snort 3 GRE detection in multiple Cisco products

Priority LOW 33CWE-128Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · Low
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

Multiple Cisco products, including Cisco Open Source Snort3, Cisco Secure Firewall Threat Defense (FTD) Software and Cisco UTD SNORT IPS Engine Software, are affected in the listed versions. Incomplete error checking when Snort 3 parses GRE packets (CWE-128) lets an unauthenticated remote attacker send a crafted GRE packet that restarts the Snort 3 Detection Engine. The restart interrupts packet inspection and causes a denial of service.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

Multiple Cisco products are affected by a vulnerability in the Snort 3 Generic Routing Encapsulation (GRE) Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection. This vulnerability is due to incomplete error checking when Snort 3 parses GRE packets. An attacker could exploit this vulnerability by sending a crafted GRE packet to a targeted device to be parsed by Snort. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a DoS condition.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00495 42nd percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
CiscoCisco Open Source Snort33.12.2.0; 3.1.2.0; 3.1.3.0; 3.1.4.0; 3.1.5.0; 3.1.6.0; 3.1.7.0; 3.1.8.0; 3.1.9.0; 3.1.10.0; 3.1.12.0; 3.1.13.0; 3.1.14.0; 3.1.15.0; 3.1.16.0; 3.1.17.0; 3.1.18.0; 3.1.19.0; 3.1.20.0; 3.1.21.0; 3.1.22.0; 3.1.23.0; 3.1.24.0; 3.1.25.0; 3.1.27.0; 3.1.28.0; 3.1.29.0; 3.1.30.0; 3.1.31.0; 3.1.32.0; 3.1.36.0; 3.1.38.0; 3.1.39.0; 3.1.40.0; 3.1.41.0; 3.1.42.0; 3.1.43.0; 3.1.45.0; 3.1.47.0; 3.1.48.0; 3.1.50.0; 3.1.51.0; 3.1.52.0; 3.1.53.0; 3.1.55.0; 3.1.56.0; 3.1.57.0; 3.1.58.0; 3.1.59.0; 3.1.60.0; 3.1.61.0; 3.1.62.0; 3.1.63.0; 3.1.64.0; 3.1.65.0; 3.1.66.0; 3.1.67.0; 3.1.69.0; 3.1.70.0; 3.1.71.0; 3.1.72.0; 3.1.73.0; 3.1.74.0; 3.1.75.0; 3.1.76.0; 3.1.77.0; 3.1.78.0; 3.1.81.0; 3.1.82.0; 3.1.83.0; 3.1.84.0; 3.2.1.0; 3.2.2.0; 3.3.0.0; 3.3.1.0; 3.3.2.0; 3.3.3.0; 3.3.4.0; 3.3.5.0; 3.3.7.0; 3.5.0.0; 3.5.1.0; 3.8.1.0; 3.6.0.0; 3.6.2.0; 3.9.3.0; 3.7.2.0; 3.7.0.0; 3.9.6.0; 3.10.0.0; 3.10.2.0; 3.7.4.0; 3.9.0.0; 3.5.2.0; 3.12.1.0; 3.6.1.0; 3.9.2.0; 3.6.3.0; 3.9.5.0; 3.7.1.0; 3.9.7.0; 3.7.3.0; 3.10.1.0; 3.9.1.0; 3.11.1.0—No fix listedCNA
CiscoCisco Secure Firewall Threat Defense (FTD) Software7.0.0; 7.0.0.1; 7.0.1; 7.0.1.1; 7.0.2; 7.2.0; 7.0.2.1; 7.0.3; 7.2.0.1; 7.0.4; 7.2.1; 7.0.5; 7.3.0; 7.2.2; 7.2.3; 7.3.1; 7.2.4; 7.0.6; 7.2.5; 7.2.4.1; 7.3.1.1; 7.4.0; 7.0.6.1; 7.2.5.1; 7.4.1; 7.2.6; 7.0.6.2; 7.4.1.1; 7.2.7; 7.2.5.2; 7.3.1.2; 7.2.8; 7.6.0; 7.4.2; 7.2.8.1; 7.0.6.3; 7.4.2.1; 7.2.9; 7.0.7; 7.7.0; 7.4.2.2; 7.2.10; 7.6.1; 7.4.2.3; 7.0.8; 7.6.2; 7.7.10; 7.7.11; 7.0.8.1; 7.6.2.1; 7.7.10.1; 7.4.2.4; 7.2.10.2; 7.4.3; 7.6.4; 10.0.0; 7.4.4; 7.0.9; 7.2.11; 7.4.7—No fix listedCNA
CiscoCisco UTD SNORT IPS Engine Software17.12.1a; 17.12.2; 17.13.1a; 17.12.3; 17.14.1a; 17.12.4; 17.12.3a; 17.15.1a; 17.16.1a; 17.12.4a; 17.15.2c; 17.12.4b; 17.15.2a; 17.12.5; 17.17.1; 17.12.5a; 17.15.3a; 17.15.3; 17.12.5b; 17.12.5c; 17.15.4; 17.18.1; 17.18.1a; 17.12.6; 17.15.4c; 17.12.5d; 17.18.2; 26.1.1; 17.15.5; 17.15.5a; 17.12.7; 17.12.7a; 17.12.7b; 17.18.3a; 17.12.8; 17.15.6; 17.18.4; 26.1.2—No fix listedCNA
  • Cisco Open Source Snort3 VendorCisco Affected 3.12.2.0; 3.1.2.0; 3.1.3.0; 3.1.4.0; 3.1.5.0; 3.1.6.0; 3.1.7.0; 3.1.8.0; 3.1.9.0; 3.1.10.0; 3.1.12.0; 3.1.13.0; 3.1.14.0; 3.1.15.0; 3.1.16.0; 3.1.17.0; 3.1.18.0; 3.1.19.0; 3.1.20.0; 3.1.21.0; 3.1.22.0; 3.1.23.0; 3.1.24.0; 3.1.25.0; 3.1.27.0; 3.1.28.0; 3.1.29.0; 3.1.30.0; 3.1.31.0; 3.1.32.0; 3.1.36.0; 3.1.38.0; 3.1.39.0; 3.1.40.0; 3.1.41.0; 3.1.42.0; 3.1.43.0; 3.1.45.0; 3.1.47.0; 3.1.48.0; 3.1.50.0; 3.1.51.0; 3.1.52.0; 3.1.53.0; 3.1.55.0; 3.1.56.0; 3.1.57.0; 3.1.58.0; 3.1.59.0; 3.1.60.0; 3.1.61.0; 3.1.62.0; 3.1.63.0; 3.1.64.0; 3.1.65.0; 3.1.66.0; 3.1.67.0; 3.1.69.0; 3.1.70.0; 3.1.71.0; 3.1.72.0; 3.1.73.0; 3.1.74.0; 3.1.75.0; 3.1.76.0; 3.1.77.0; 3.1.78.0; 3.1.81.0; 3.1.82.0; 3.1.83.0; 3.1.84.0; 3.2.1.0; 3.2.2.0; 3.3.0.0; 3.3.1.0; 3.3.2.0; 3.3.3.0; 3.3.4.0; 3.3.5.0; 3.3.7.0; 3.5.0.0; 3.5.1.0; 3.8.1.0; 3.6.0.0; 3.6.2.0; 3.9.3.0; 3.7.2.0; 3.7.0.0; 3.9.6.0; 3.10.0.0; 3.10.2.0; 3.7.4.0; 3.9.0.0; 3.5.2.0; 3.12.1.0; 3.6.1.0; 3.9.2.0; 3.6.3.0; 3.9.5.0; 3.7.1.0; 3.9.7.0; 3.7.3.0; 3.10.1.0; 3.9.1.0; 3.11.1.0 Fixed in — No fix listed CNA
  • Cisco Secure Firewall Threat Defense (FTD) Software VendorCisco Affected 7.0.0; 7.0.0.1; 7.0.1; 7.0.1.1; 7.0.2; 7.2.0; 7.0.2.1; 7.0.3; 7.2.0.1; 7.0.4; 7.2.1; 7.0.5; 7.3.0; 7.2.2; 7.2.3; 7.3.1; 7.2.4; 7.0.6; 7.2.5; 7.2.4.1; 7.3.1.1; 7.4.0; 7.0.6.1; 7.2.5.1; 7.4.1; 7.2.6; 7.0.6.2; 7.4.1.1; 7.2.7; 7.2.5.2; 7.3.1.2; 7.2.8; 7.6.0; 7.4.2; 7.2.8.1; 7.0.6.3; 7.4.2.1; 7.2.9; 7.0.7; 7.7.0; 7.4.2.2; 7.2.10; 7.6.1; 7.4.2.3; 7.0.8; 7.6.2; 7.7.10; 7.7.11; 7.0.8.1; 7.6.2.1; 7.7.10.1; 7.4.2.4; 7.2.10.2; 7.4.3; 7.6.4; 10.0.0; 7.4.4; 7.0.9; 7.2.11; 7.4.7 Fixed in — No fix listed CNA
  • Cisco UTD SNORT IPS Engine Software VendorCisco Affected 17.12.1a; 17.12.2; 17.13.1a; 17.12.3; 17.14.1a; 17.12.4; 17.12.3a; 17.15.1a; 17.16.1a; 17.12.4a; 17.15.2c; 17.12.4b; 17.15.2a; 17.12.5; 17.17.1; 17.12.5a; 17.15.3a; 17.15.3; 17.12.5b; 17.12.5c; 17.15.4; 17.18.1; 17.18.1a; 17.12.6; 17.15.4c; 17.12.5d; 17.18.2; 26.1.1; 17.15.5; 17.15.5a; 17.12.7; 17.12.7a; 17.12.7b; 17.18.3a; 17.12.8; 17.15.6; 17.18.4; 26.1.2 Fixed in — No fix listed CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:*——Cisco
  • cpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:* Versions — — ·Cisco

Remediation

The sources list no fixed version for Cisco Open Source Snort3, Cisco Secure Firewall Threat Defense (FTD) Software or Cisco UTD SNORT IPS Engine Software.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Timeline

  1. 2026-10-21 Threatist record created from CVE-2026-20179
  2. 2026-10-21 Alias added: GHSA-9v2c-x8g8-r7m4
  3. 2026-10-22 CISA SSVC decision points changed
  4. 2026-10-22 Priority changed: MEDIUM → LOW

References

Other 1

  • TI-2026-74174 Arbitrary file write in Cisco Secure Email Gateway via AMP feature KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-53490 Cisco Catalyst SD-WAN Manager System Account Authorization Bypass Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-53489 Cisco Secure Email Gateway SQL Injection Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-53488 Cisco Identity Services Engine Authentication Bypass Vulnerability KEVCVSS 3.1CRITICAL 10.0
  • TI-2026-16388 Cisco Catalyst SD-WAN Controller Authentication Bypass Vulnerability KEVCVSS 3.1CRITICAL 10.0
  • TI-2026-16344 Cisco Secure Firewall Management Center Software Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 10.0
See all 7059 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences