CVE-2017-12240VulnerabilityPublished 03/03/2022Updated 10/24/2026

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

Affects Cisco IOS and IOS XE SoftwareSource CISA KEV

Severity

High

No CVSS score published yet

Exploitation: Actively exploited – in CISA KEV since 03/03/2022
KEV deadline: 03/24/2022
EPSS: 13.8% chance of exploitation in 30 days – higher than 96% of CVEs

What to do

CISA required action

Apply updates per vendor instructions.

nvd.nist.gov/vuln/detail/CVE-2017-12240 (opens in a new tab)

Description

CVE-2017-12240 is a high-severity vulnerability in the DHCP relay subsystem of Cisco IOS and IOS XE Software. It allows an unauthenticated remote attacker to execute arbitrary code and gain full control over the affected system. This vulnerability has been exploited in the wild. No specific affected versions or patch information are provided in the available data.

Summary

The Dynamic Host Configuration Protocol (DHCP) relay subsystem in Cisco IOS and IOS XE Software contains a vulnerability (CVE-2017-12240) that permits unauthenticated remote attackers to execute arbitrary code, potentially leading to full system compromise. This vulnerability has been observed in active exploitation scenarios. The lack of detailed version information and patch references limits precise remediation guidance.

Impact

Successful exploitation allows an unauthenticated remote attacker to execute arbitrary code on affected Cisco IOS and IOS XE devices, resulting in full system control. This can lead to significant operational disruption and compromise of network infrastructure. The vulnerability has been exploited in the wild, indicating active threat actor interest and real-world risk.

Mitigation

Patch status is not yet confirmed — check the Cisco vendor advisory for current remediation guidance. Due to the critical nature of this vulnerability and known exploitation, it is recommended to monitor Cisco's official advisories for patches or workarounds and apply them promptly once available.

Weaknesses

CWE-20Improper Input Validation (opens in a new tab)

What to do

Description

AnalysisAI-generated, updated 10/24/2026, 10:27:25 UTC

Weaknesses

References

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