# CVE-2017-12240: Cisco IOS and IOS XE Software DHCP Remote Code Execution Vulnerability

> CVE-2017-12240: Cisco IOS and IOS XE Software DHCP Remote Code Execution Vulnerability. CVSS 9.8 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2017-12240
Last updated: 2026-01-12T21:47:19Z

- Published: 2017-09-28 07:00 UTC · Updated: 2026-01-12 21:47 UTC · Assigner: cisco
- CVSS: 9.8 (CVSS 3.1) · Severity: Critical · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS: 13.8%, 96th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2022-03-03, federal due date 2022-03-24, ransomware use: Unknown
- CWE: CWE-20

## Description

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.

## CISA required action

Apply updates per vendor instructions.

## Affected vendors and products

- n/a: Cisco IOS and IOS XE

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2017-12240)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2017-12240)
- [https://quickview.cloudapps.cisco.com/quickview/bug/CSCsm45390](https://quickview.cloudapps.cisco.com/quickview/bug/CSCsm45390)
- [https://quickview.cloudapps.cisco.com/quickview/bug/CSCuw77959](https://quickview.cloudapps.cisco.com/quickview/bug/CSCuw77959)
- [https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-dhcp](https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-dhcp)
- [http://www.securityfocus.com/bid/101034](http://www.securityfocus.com/bid/101034)
- [http://www.securitytracker.com/id/1039445](http://www.securitytracker.com/id/1039445)

---

_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


---
Canonical: https://rewindex.com/cve/CVE-2017-12240 · Markdown: https://rewindex.com/cve/CVE-2017-12240.md · JSON: https://rewindex.com/api/v1/cves/CVE-2017-12240 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T01:58:49.573Z