What it is
CVE-2017-12240 is an unauthenticated vulnerability affecting Cisco Cisco IOS and IOS XE. The DHCP relay subsystem of Cisco IOS 12.2 through 15.6 and Cisco IOS XE Software contains a vulnerability that could allow an...
Vulnerability report
Exploited in the wild
Confirmed confidence
In CISA KEV
CVE-2017-12240
Cisco IOS and IOS XE Denial of Service
Cisco / Cisco IOS and IOS XE · Cisco IOS and IOS XE
- Severity
- CVSS 9.8 · Critical
- Confidence
- Confirmed
- Exploit status
- Exploited in the wild
- EPSS
- 13.9%
- First observed
- —
- Last observed
- —
Decision summary
What security teams need to know first
Direct answers before the deeper technical record.
Is it exploited?
Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.
Who is affected?
Cisco / Cisco IOS and IOS XE cisco ios and ios xe.
What should we do?
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
Overview
Cisco IOS and IOS XE Denial of Service
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.
Vendor
Product
Affected
Status
n/a
Cisco IOS and IOS XE
Cisco IOS and IOS XE
Affected
- Published
- 28 Sep 2017
- Exploitation Reported
- 03 Mar 2022
- Attack vector
- Remote
- Complexity
- Low
- Privileges
- None
- User interaction
- None
Tags
ios
edge
cisa
CVE References
- CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2017-12240
- 101034 securityfocus.com · VDB Entry http://www.securityfocus.com/bid/101034
- 1039445 securitytracker.com · VDB Entry http://www.securitytracker.com/id/1039445
- quickview.cloudapps.cisco.com/quickview/bug/CSCuw77959 quickview.cloudapps.cisco.com · CVE Record https://quickview.cloudapps.cisco.com/quickview/bug/CSCuw77959
- quickview.cloudapps.cisco.com/quickview/bug/CSCsm45390 quickview.cloudapps.cisco.com · CVE Record https://quickview.cloudapps.cisco.com/quickview/bug/CSCsm45390
- tools.cisco.com/security/center/content/CiscoSecurityAdvisor... tools.cisco.com · CVE Record https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory...
Exploitation evidence
Why KEV Intelligence marks this CVE as exploited
Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.
Exploited in the wild
CISA
Independent exploitation attestation added to the KEV Intelligence record.
Known exploited vulnerability sources
Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.
Learn about Pro API access| Source | Added |
|---|---|
| CISA First | 2022-03-03 00:00 UTC |
Detection
Operational artifacts and observed signals
Make the evidence actionable in scanner, SOC, and edge-control workflows.
Observed signals
- Request targets
- 0
- User-Agents
- 0
Raw values available in Pro and Enterprise.
Scanner coverage
No scanner integrations recorded yet.
Virtual patch status
No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.
Learn about virtual patches →No detection artifacts or sensor request patterns are available for this CVE yet.
Check back as sensor telemetry and scanner integrations are updated.
Risk and context
Severity, weaknesses, and research context
CVSS v3.1
9.8
Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
13.9%
Weaknesses
All CVSS Scores
CVSS v3.1
9.8
Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v2.0
10.0
High
AV:N/AC:L/Au:N/C:C/I:C/A:C
Timeline
From disclosure to observed exploitation
-
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
CVE published
Vulnerability disclosed publicly
-
CVE ID reserved
Identifier reserved by the CNA
Pro API
Automate this intelligence
Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
- Evidence confidence and provenance
- First-party sensor telemetry
- PoC and scanner references
- Affected versions and enrichment
- Automation-ready JSON delivery
GET /api/v2/pro/kevs/CVE-2017-12240
Free JSON includes basic KEV fields{
"cve_id": "CVE-2017-12240",
"confidence": "Confirmed",
"cvss_score": 9.8,
"cvss_estimated": false,
"epss_score": 0.13883,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "attempts": 0, "sensors": 0 }
}Early warning alerts
Get alerts on high-impact exploitation
Receive curator-selected alerts when exploitation activity warrants attention. Each alert includes the evidence and context needed to decide what requires attention now.