Read the docs
TI-2026-78818 Aliases CVE-2026-20218GHSA-vvhg-cxrm-qp98

Buffer overflow in Cisco Snort 3 VBA decompression causes DoS

Priority LOW 33CWE-121Published · 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

Cisco Open Source Snort3, Cisco Secure Firewall Threat Defense (FTD) Software and Cisco UTD SNORT IPS Engine Software are affected. The Snort 3 Visual Basic for Applications decompression engine does not check ranges properly when it decompresses user-controlled VBA data, which causes a stack buffer overflow (CWE-121). An unauthenticated remote attacker can send crafted VBA data to a targeted device and cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a denial of service.

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

Description from the CNA

A vulnerability in the Snort 3 Visual Basic for Applications (VBA) Decompression Engine of multiple Cisco products could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS) condition.   This vulnerability is due to improper range checking when Snort 3 decompresses VBA data, which is user controlled. An attacker could exploit this vulnerability by sending crafted VBA data to the Snort 3 Detection Engine of a targeted device. A successful exploit could allow the attacker to cause an overflow of stack data, which could result in a DoS condition.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0063 50th 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) Software7.2.0; 7.2.0.1; 7.2.1; 7.3.0; 7.2.2; 7.2.3; 7.3.1; 7.2.4; 7.2.5; 7.2.4.1; 7.3.1.1; 7.4.0; 7.2.5.1; 7.4.1; 7.2.6; 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; 7.4.2.1; 7.2.9; 7.7.0; 7.4.2.2; 7.2.10; 7.6.1; 7.4.2.3; 7.6.2; 7.7.10; 7.7.11; 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; 7.2.11; 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 7.2.0; 7.2.0.1; 7.2.1; 7.3.0; 7.2.2; 7.2.3; 7.3.1; 7.2.4; 7.2.5; 7.2.4.1; 7.3.1.1; 7.4.0; 7.2.5.1; 7.4.1; 7.2.6; 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; 7.4.2.1; 7.2.9; 7.7.0; 7.4.2.2; 7.2.10; 7.6.1; 7.4.2.3; 7.6.2; 7.7.10; 7.7.11; 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; 7.2.11; 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-2026-20218
  2. 2026-10-21 Alias added: GHSA-vvhg-cxrm-qp98
  3. 2026-10-22 CISA SSVC decision points changed
  4. 2026-10-22 Priority changed: MEDIUM → LOW
  5. 2026-10-28 EPSS moved to the 50th–90th percentile

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