Cyber Resilience

CVE-2023-20086

Cisco Adaptive Security Appliance Software 9.12.1 … 9.8.4.8

Published
01 November 2023
Modified
11 August 2026
Patch / advisory
View advisory
CVSS Score v3.1 8.6
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS Score 0.0065 48th percentile
Risk Priority 63 floored blend · peak EPSS

Summary

CVE-2023-20086 is a high-severity Uncaught Exception (CWE-248) vulnerability in Cisco Adaptive Security Appliance Software. Its CVSS base score is 8.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Endpoint Denial of Service (T1499); ranked at the 48th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

A10:2025 Mishandling of Exceptional Conditions

EU & UK References

Vulnerability Data

A vulnerability in ICMPv6 processing of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. This vulnerability is due to improper processing…

more

of ICMPv6 messages. An attacker could exploit this vulnerability by sending crafted ICMPv6 messages to a targeted Cisco ASA or FTD system with IPv6 enabled. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

CWE(s)
CWE-248NVD-CWE-noinfo

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
attack.mitre.org →
T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-20353Same product: Cisco Adaptive Security Appliance Software
CVE-2024-20426Same product: Cisco Adaptive Security Appliance Software
CVE-2026-20106Same product: Cisco Adaptive Security Appliance Software
CVE-2026-20105Same product: Cisco Adaptive Security Appliance Software
CVE-2023-20095Same product: Cisco Adaptive Security Appliance Software
CVE-2024-20481Same product: Cisco Adaptive Security Appliance Software
CVE-2026-20014Same product: Cisco Adaptive Security Appliance Software
CVE-2026-20015Same product: Cisco Adaptive Security Appliance Software
CVE-2026-20021Same product: Cisco Adaptive Security Appliance Software
CVE-2024-20493Same product: Cisco Adaptive Security Appliance Software

Affected Assets

cisco
adaptive security appliance software
9.12.1, 9.12.1.2, 9.12.1.3, 9.12.2, 9.12.2.1
cisco
secure firewall threat defense
6.2.3, 6.2.3.1, 6.2.3.10, 6.2.3.11, 6.2.3.12

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SC-24 Fail in Known State
addresses: CWE-248

Prevents abrupt termination from uncaught exceptions by requiring a defined, preserved-state failure mode.

SI-17 Fail-safe Procedures
addresses: CWE-248

Requires pre-defined safe responses for uncaught exceptions so they do not result in undefined or insecure program termination.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices explicitly require structured exception handling to prevent uncaught exceptions from reaching production.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect uncaught exceptions before production deployment.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle includes exception-handling standards that reduce uncaught exceptions.

A.8.26 Application security requirements partial match
prevents

Application security requirements typically mandate robust error and exception handling.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles call for centralized, comprehensive exception management.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly require catching and handling exceptions to prevent crashes or leaks.

References