TI-2018-10959 Aliases CVE-2018-15399 GHSA-29pp-9vf2-x8xr

Cisco Adaptive Security Appliance TCP Syslog Denial of Service Vulnerability

LOW 34CWE-400Published 2018-10-05 · Updated 2024-11-26

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: High
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-400.

Summary

A vulnerability in the TCP syslog module of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to exhaust the 1550-byte buffers on an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to a missing boundary check in an internal function. An attacker could exploit this vulnerability by establishing a man-in-the-middle position between an affected device and its configured TCP syslog server and then maliciously modifying the TCP header in segments that are sent from the syslog server to the affected device. A successful exploit could allow the attacker to exhaust buffer on the affected device and cause all TCP-based features to stop functioning, resulting in a DoS condition. The affected TCP-based features include AnyConnect SSL VPN, clientless SSL VPN, and management connections such as Secure Shell (SSH), Telnet, and HTTPS.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.01844 79th 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: No
Technical impact: Partial

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

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Cisco	Cisco Adaptive Security Appliance (ASA) Software	all versions	—	No fix listed	CNA

Cisco Adaptive Security Appliance (ASA) Software VendorCisco Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 3

CPE	Versions	Role	Vendor
cpe:2.3:o:cisco:adaptive_security_appliance_software:9.4\(4\):::::::*	9.4(4)	Vulnerable	Cisco
cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8\(2\):::::::*	9.8(2)	Vulnerable	Cisco
cpe:2.3:a:cisco:secure_firewall_threat_defense:6.2.0:::::::*	6.2.0	Vulnerable	Cisco

cpe:2.3:o:cisco:adaptive_security_appliance_software:9.4\(4\):*:*:*:*:*:*:* Versions 9.4(4) Vulnerable ·Cisco
cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8\(2\):*:*:*:*:*:*:* Versions 9.8(2) Vulnerable ·Cisco
cpe:2.3:a:cisco:secure_firewall_threat_defense:6.2.0:*:*:*:*:*:*:* Versions 6.2.0 Vulnerable ·Cisco

Remediation

No fixed version listed by the sources yet.

Timeline

2026-10-02 Threatist record created from CVE-2018-15399
2026-10-03 Alias added: GHSA-29pp-9vf2-x8xr

References

Advisory 1

20181003 Cisco Adaptive Security Appliance TCP Syslog Denial of Service Vulnerability

TI-2025-14628 Buffer overflow in Cisco Secure Firewall Adaptive Security Appliance Software KEVCVSS 3.1CRITICAL 9.9
TI-2016-05454 Buffer overflow in Cisco Adaptive Security Appliance (ASA) Software through 9.4.2.3 on… KEVCVSS 3.1HIGH 8.8
TI-2023-06973 Authentication bypass in Cisco Adaptive Security Appliance Software KEVCVSS 3.1CRITICAL 9.1
TI-2026-82192 Denial of service in Cisco Secure Firewall ASA and FTD SSL VPN KEVCVSS 3.1HIGH 8.6
TI-2026-16533 Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense… KEVCVSS 3.1HIGH 8.6
TI-2025-14657 Missing authorization in Cisco Secure Firewall Adaptive Security Appliance Software KEVCVSS 3.1HIGH 8.6

See all 354 →

Sources

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