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CVE-2017-12240

Cisco IOS and IOS XE Software DHCP Remote Code Execution

9.8 CRITICALActively exploited (CISA KEV)EPSS 13.8%
  1. Published28 Sept 2017
  2. Added to CISA KEV3 Mar 2022
  3. Remediation due24 Mar 2022
Actively exploited (CISA KEV)

The Dynamic Host Configuration Protocol (DHCP) relay subsystem of Cisco IOS 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.

Added to KEV: 3 Mar 2022Federal remediation due: 24 Mar 2022

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Cisco iOS≥ 12.2 ≤ 15.6

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

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Frequently asked

Is CVE-2017-12240 being actively exploited?

Yes. CVE-2017-12240 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 3 Mar 2022.

How severe is CVE-2017-12240?

CVE-2017-12240 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 13.8% probability of exploitation.

Which products are affected by CVE-2017-12240?

Affected products include Cisco iOS.

How do I fix CVE-2017-12240?

Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2017-12240 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.