Cyber Resilience

CVE-2016-6366

Memory Safety in Cisco Adaptive Security Appliance Software 7.2.1 – 9.0.4.40

CISA KEVActive ExploitationEUVD ExploitedPublic PoCMemory Safety
Published
18 August 2016
Modified
22 April 2026
KEV Added
24 May 2022
Patch / advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.88 99.7th percentile
Risk Priority 90 floored blend · peak EPSS

Summary

CVE-2016-6366 is a high-severity Classic Buffer Overflow (CWE-120) vulnerability in Cisco Adaptive Security Appliance Software. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 0.3% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2016-6366 is a buffer overflow vulnerability, tracked as Bug ID CSCva92151 and also known as EXTRABACON, that affects Cisco Adaptive Security Appliance (ASA) Software through version 9.4.2.3. The flaw impacts multiple device families including ASA 5500, ASA 5500-X, ASA Services Module, ASA 1000V, ASAv, Firepower 9300 ASA Security Module, PIX, and FWSM when processing crafted IPv4 SNMP packets. It is classified under CWE-120 with a CVSS 3.1 base score of 8.8.

Remote authenticated users can exploit the issue over the network by sending specially crafted IPv4 SNMP packets, enabling them to execute arbitrary code on the affected device with high impact to confidentiality, integrity, and availability.

Cisco published Security Advisory cisco-sa-20160817-asa-snmp along with related ERP and blog posts discussing the Shadow Brokers disclosure that referenced this vulnerability; the references point to official mitigation guidance and patch availability for supported releases. The flaw gained additional attention due to its association with the EXTRABACON tool in the Shadow Brokers leak of purported NSA exploits.

EU & UK References

Vulnerability Data

Buffer overflow in Cisco Adaptive Security Appliance (ASA) Software through 9.4.2.3 on ASA 5500, ASA 5500-X, ASA Services Module, ASA 1000V, ASAv, Firepower 9300 ASA Security Module, PIX, and FWSM devices allows remote authenticated users to execute arbitrary code via…

more

crafted IPv4 SNMP packets, aka Bug ID CSCva92151 or EXTRABACON.

CWE(s)
KEV Date Added
24 May 2022

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-20333Same product: Cisco Adaptive Security Appliance Softwareboth on KEV
CVE-2016-6367Same product: Cisco Adaptive Security Appliance Softwareboth on KEV
CVE-2020-3452Same product: Cisco Adaptive Security Appliance Softwareboth on KEV
CVE-2026-20100Same product: Cisco Adaptive Security Appliance Software
CVE-2024-20454Same vendor: Cisco
CVE-2023-20162Same vendor: Cisco
CVE-2024-20313Same vendor: Cisco
CVE-2025-20352Same vendor: Ciscoboth on KEV
CVE-2023-20161Same vendor: Cisco
CVE-2023-20157Same vendor: Cisco

Affected Assets

cisco
pix firewall software
all versions
cisco
adaptive security appliance software
7.2.1 — 9.0.4.40 · 9.1.1 — 9.1.7\(9\) · 9.2.0 — 9.2.4\(14\)
cisco
asa 1000v cloud firewall software
8.7.1, 8.7.1.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)
  • V5.2.1

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.

addresses: CWE-120

Platform-independent managed code eliminates the need for unchecked native buffer copies that are the root cause of classic buffer overflows.

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 development practices directly enforce bounds checking and input validation that prevent classic buffer overflows.

ID.RA-01 partial match
prevents

Vulnerability identification processes such as code review or scanning detect classic buffer overflows before exploitation.

PR.PS-02 partial match
prevents

Routine patching replaces vulnerable code containing unchecked buffer copies with corrected versions.

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.

prevents

Secure coding directly requires bounds-checked memory operations, addressing the root cause of CWE-120.

finds

Security testing in development and acceptance can detect buffer overflows through fuzzing and static analysis, though it does not prevent them at the source.

prevents

Secure development life cycle mandates processes that can include input validation and bounds checking to prevent buffer overflows.

prevents

Application security requirements can specify input-size validation and safe buffer handling to mitigate classic buffer overflows.

prevents

Secure system architecture and engineering principles promote defensive coding patterns that reduce the likelihood of unchecked buffer copies.

References