Skip to content
Patcharo
Back to the results

Vulnerabilities

CriticalKEV

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

CVE-2017-12240 · Cisco IOS and IOS XE · CVSS 9.8 · KEV

In brief

Severity · CVSS
Critical9.8CVSS 3.1, Critical
EPSS
14%
CISA KEV
Known exploited, listed since 3 Mar 2022
CERT-FR
No advisory or alert referenced in the catalog
Vendor
Cisco
Published · Modified
·
Last verified

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.

Weakness: CWE-20, CWE-119

Title, description and the vendor's statements are quoted from the CVE record; a vendor's advisory is summarised in Patcharo's words, with a link.

Affected and fixed versions

Per product and release branch, as the vendor's CVE record and official advisory state them. A fixed release is shown only when a document names it: the vendor's, or CERT-FR's for Check Point, with its source.

Cisco IOS and IOS XE

Source: CVE-2017-12240cisco-sa-20170927-dhcp

  1. —
    Affected versionsCisco IOS and IOS XE
    First fixed releaseNot published in the sources followed

The vendor states fixes are available; the releases per branch are in its advisory.

Remediation

Fix available

Vendor fix

Cisco has released updates that fix this vulnerability; its advisory lists them.

SourceCisco Security Advisory cisco-sa-20170927-dhcp· revised 17 Dec 2022

Workarounds (vendor)

Cisco states in its advisory that no workaround is available.

SourceCisco Security Advisory cisco-sa-20170927-dhcp

CISA KEV required action

Apply updates per vendor instructions.

CISA due date:

SourceCISA KEV

Last verified 1 Oct 2026 at 09:31 UTC

Known exploitation

Added to CISA KEV on 3 Mar 2022

Federal remediation due date: 24 Mar 2022

The CISA required action is shown under Remediation.

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

CERT-FR

No CERT-FR advisory or alert of the last two years references this CVE, for the vendors Patcharo covers.

Timeline

  1. Published by the source
  2. Added to CISA KEV
  3. CISA remediation due date
  4. Source record last modified
  5. EPSS score computed
  6. Last verified by Patcharo

Official sources

Vendor advisory

References

Cisco · CISA Known Exploited Vulnerabilities · NVD · FIRST EPSS · Cisco Security Advisory cisco-sa-20170927-dhcp

How Patcharo reads this

Affected and fixed releases come from the vendor's structured statements and are matched against exact versions; CVSS from NVD, exploitation from CISA KEV and the vendor's own advisory, probability from FIRST EPSS. Missing data stays Unknown and never becomes Not affected.

Read the methodologyRead the guide: Cisco Secure Firewall release trains: Threat Defense, Management Center and ASA versions explained