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CVE-2017-12240

74
FAUCET Score

CVE-2017-12240 is a critical buffer overflow vulnerability in the DHCP relay subsystem of Cisco IOS (versions 12.2-15.6) and Cisco IOS XE Software. This flaw allows an unauthenticated, remote attacker to execute arbitrary code, gaining full control of the affected system, or trigger a denial of service by causing a reload. With a CVSS score of 9.8 (CRITICAL), it is easily exploitable over the network with low attack complexity, posing a significant risk to confidentiality, integrity, and availability. This vulnerability is actively exploited in the wild, as indicated by its presence in the KEV catalog, and has garnered substantial community discussion and media coverage, despite no public exploit code being readily available through common frameworks.

Impacted Technologies

VendorProductVersion(s)CPE
>= 12.2, <= 15.6CPE matchmatch criteria
cpe:2.3:o:cisco:ios:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
13.88%
Probability of exploitation in next 30 days
EPSS Percentile
96.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
Added to KEV · Mar 3, 2022
This CVE's current EPSS score of 0.1388 is in the 92nd percentile among its peer group of 36,829 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

ciscovendor investigatingvia nvd_reference
View patch

References

cisa.gov / known-exploited-vulnerabilities-catalog
US Government Resource
quickview.cloudapps.cisco.com / quickview/bug/CSCsm45390
Vendor Advisory
quickview.cloudapps.cisco.com / quickview/bug/CSCuw77959
Vendor Advisory
tools.cisco.com / security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-dhcp
Vendor Advisory
securityfocus.com / bid/101034
Broken LinkThird Party AdvisoryVDB Entry
securitytracker.com / id/1039445
Broken LinkThird Party AdvisoryVDB Entry