Cyber Resilience

CVE-2023-20109

Memory Safety in Cisco Ios 12.4\(22\)md … 15.9\(3\)m7a

CISA KEVActive ExploitationEUVD ExploitedMemory Safety
Published
27 September 2023
Modified
28 October 2025
KEV Added
10 October 2023
Patch / advisory
CVSS Score v3.1 6.6
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.023 82th percentile
Risk Priority 75 floored blend · peak EPSS

Summary

CVE-2023-20109 is a medium-severity Out-of-bounds Write (CWE-787) vulnerability in Cisco Ios. Its CVSS base score is 6.6 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 18% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

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

A vulnerability in the Cisco Group Encrypted Transport VPN (GET VPN) feature of Cisco IOS Software and Cisco IOS XE Software stems from insufficient validation of attributes in the Group Domain of Interpretation (GDOI) and G-IKEv2 protocols. The flaw, tracked as CVE-2023-20109 with a CVSS score of 6.6, is also associated with CWE-787 and affects devices configured for GET VPN operations.

An authenticated remote attacker who has already obtained administrative control of either a group member or a key server can exploit the issue by compromising an installed key server or redirecting a group member to an attacker-controlled key server. Successful exploitation enables arbitrary code execution with full system control or triggers a device reload resulting in denial of service.

The Cisco Security Advisory at sec.cloudapps.cisco.com provides mitigation guidance and software updates, while CISA lists the CVE in its Known Exploited Vulnerabilities catalog, indicating confirmed in-the-wild exploitation. The current EPSS score of 0.0063 reflects limited but non-zero exploitation probability.

EU & UK References

Vulnerability Data

A vulnerability in the Cisco Group Encrypted Transport VPN (GET VPN) feature of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker who has administrative control of either a group member or a key server…

more

to execute arbitrary code on an affected device or cause the device to crash. This vulnerability is due to insufficient validation of attributes in the Group Domain of Interpretation (GDOI) and G-IKEv2 protocols of the GET VPN feature. An attacker could exploit this vulnerability by either compromising an installed key server or modifying the configuration of a group member to point to a key server that is controlled by the attacker. A successful exploit could allow the attacker to execute arbitrary code and gain full control of the affected system or cause the affected system to reload, resulting in a denial of service (DoS) condition. For more information, see the Details ["#details"] section of this advisory.

CWE(s)
KEV Date Added
10 October 2023

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.
T1211 Exploitation for Stealth Stealth
Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.
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-2024-20308Same product: Cisco Ios
CVE-2024-20433Same product: Cisco Ios
CVE-2018-0171Same product: Cisco Iosboth on KEV
CVE-2022-20701Same vendor: Ciscoboth on KEV
CVE-2020-3118Same vendor: Ciscoboth on KEV
CVE-2022-20700Same vendor: Ciscoboth on KEV
CVE-2018-0172Same product: Cisco Iosboth on KEV
CVE-2024-20501Same vendor: Cisco
CVE-2024-20357Same vendor: Cisco
CVE-2023-20213Same vendor: Cisco

Affected Assets

cisco
ios
12.4\(22\)md, 12.4\(22\)md1, 12.4\(22\)md2, 12.4\(22\)mda, 12.4\(22\)mda1
cisco
ios xe
16.1.1, 16.1.2, 16.1.3, 16.10.1, 16.10.1a

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.

addresses: CWE-787

Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.

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 (static analysis, bounds checking, code review) are the primary means of preventing out-of-bounds writes.

ID.RA-01 partial match
prevents

Vulnerability scanning and recording can discover out-of-bounds write flaws so they can be remediated.

PR.PS-02 partial match
prevents

Patching or replacing vulnerable software directly eliminates known instances of this coding weakness.

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.

finds

Security testing in development and acceptance can detect and prevent out-of-bounds write defects.

prevents

Secure development life cycle mandates practices that prevent out-of-bounds writes.

prevents

Application security requirements can specify bounds-checking and safe memory handling.

prevents

Secure architecture and engineering principles reduce the likelihood of buffer overflows.

prevents

Secure coding directly addresses out-of-bounds writes through language choice and coding standards.

prevents

Change management can enforce review gates that catch unsafe memory operations before deployment.

References