Cisco IOS and IOS XE Software DHCP Remote Code Execution Vulnerability
- Severity
- Critical9.8CVSS 3.1, Critical
- EPSS
- 14%
- Published
- 28 Sept 2017
- Updated
- 17 Jun 2026
Description
Title, description and vendor guidance are quoted from the source records.
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.
Weakness: CWE-20, CWE-119
Known exploited
Added to CISA KEV on 3 Mar 2022
Federal remediation due date: 24 Mar 2022
Required action: Apply updates per vendor instructions.
Exploit prediction
14% probability of exploitation in the next 30 days (percentile 96%).
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected products
Patcharo shows this vulnerability for information but does not match versions for this product yet.
- n/a Cisco IOS and IOS XE · Cisco IOS and IOS XE
References
- https://quickview.cloudapps.cisco.com/quickview/bug/CSCuw77959(opens in a new tab)
- https://quickview.cloudapps.cisco.com/quickview/bug/CSCsm45390(opens in a new tab)
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-dhcp(opens in a new tab)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2017-12240(opens in a new tab)
Provenance
Every fact on this page comes from the sources below. Nothing is written by an AI.
- Cisco (CVE record)
- Cisco (CVE record) · 27 Sept 2026, 23:46 UTC · Parser patcharo-cve5/1.1.0
- CISA Known Exploited Vulnerabilities
- CISA Known Exploited Vulnerabilities · 27 Sept 2026, 23:42 UTC · Parser patcharo-kev/1.0.0
- NVD
- NVD · 27 Sept 2026, 23:44 UTC · Parser patcharo-nvd/1.0.0
- FIRST EPSS
- FIRST EPSS · 27 Sept 2026, 23:46 UTC · Parser patcharo-epss/1.0.0
Last verified: 28 Sept 2026, 02:31 UTC