CVE DATABASE / CVE-2017-12240
CVE-2017-12240
Cisco IOS and IOS XE Software DHCP Remote Code Execution Vulnerability
Confirmed exploited in the wild. Added 2022-03-03.
Federal remediation due 2022-03-24.
Required action: Apply updates per vendor instructions.
Summary
The DHCP relay subsystem of Cisco IOS 12.2 through 15.6 and Cisco IOS XE Software contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code and gain full control of an affected system. The attacker could also cause an affected system to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to a buffer overflow condition in the DHCP relay subsystem of the affected software. An attacker could exploit this vulnerability by sending a crafted DHCP Version 4 (DHCPv4) packet to an affected system. 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 DoS condition. Cisco Bug IDs: CSCsm45390, CSCuw77959.
CVSS 3.1 breakdown
| Base score | 9.8 (CRITICAL) |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Attack vector | NETWORK |
| Attack complexity | LOW |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity | HIGH |
| Availability | HIGH |
Weakness type (CWE)
Affected products
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References
- http://www.securityfocus.com/bid/101034
- http://www.securitytracker.com/id/1039445
- https://quickview.cloudapps.cisco.com/quickview/bug/CSCsm45390
- https://quickview.cloudapps.cisco.com/quickview/bug/CSCuw77959
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-dhcp
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2017-12240
Data: NIST NVD + CISA KEV. NVD last modified 2026-04-21. Always verify against the vendor advisory before acting.