CVE-2023-20109
Cisco IOS and IOS XE Group Encrypted Transport VPN Out-of-Bounds Write Vulnerability
Cisco IOS and IOS XE
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 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.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 10 October 2023. US federal agencies were required to remediate it by 31 October 2023.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 2.5%, which is higher than 84.2% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
Frequently asked questions
Is CVE-2023-20109 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2023-20109.
What does CVE-2023-20109 affect?
CVE-2023-20109 affects Cisco IOS and IOS XE. 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 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.
How severe is CVE-2023-20109?
CVE-2023-20109 is rated MEDIUM with a CVSS base score of 6.6. EPSS puts the probability of exploitation in the next 30 days at 2.5%, higher than 84.2% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 31 October 2023.
How should organisations respond to CVE-2023-20109?
Apply the vendor patch for Cisco IOS and IOS XE as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.