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CVE-2020-3120

23
FAUCET Score

CVE-2020-3120 is a denial-of-service vulnerability in the Cisco Discovery Protocol (CDP) implementation across Cisco FXOS, IOS XR, and NX-OS Software. An unauthenticated, adjacent attacker can exploit this flaw by sending a malicious CDP packet, leading to system memory exhaustion and a device reload. This vulnerability has a CVSS score of 6.5 (Medium) due to its low attack complexity and the attacker's need for Layer 2 adjacency, but it can result in a complete denial of service. While there are no known public exploits or Metasploit modules, the vulnerability has garnered significant community discussion and media coverage, indicating awareness despite its inactive status on the CISA KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.3.1.173CPE matchmatch criteria
cpe:2.3:o:cisco:firepower_extensible_operating_system:*:*:*:*:*:*:*:*
>= 2.6, < 2.6.1.187CPE matchmatch criteria
cpe:2.3:o:cisco:firepower_extensible_operating_system:*:*:*:*:*:*:*:*
>= 2.7, < 2.7.1.106CPE matchmatch criteria
cpe:2.3:o:cisco:firepower_extensible_operating_system:*:*:*:*:*:*:*:*
2.4CPE matchmatch criteria
cpe:2.3:o:cisco:fxos:2.4:*:*:*:*:*:*:*
5.2.5CPE matchmatch criteria
cpe:2.3:o:cisco:ios_xr:5.2.5:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

7.4HIGH

CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
4.0
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.64%
Probability of exploitation in next 30 days
EPSS Percentile
73.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0164 is in the 95th percentile among its peer group of 1,802 CVEs.

Social Chatter

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

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

ciscovendor investigatingvia nvd_reference
View patch

References

packetstormsecurity.com / files/156203/Cisco-Discovery-Protocol-CDP-Remote-Device-Takeover.html
Third Party AdvisoryVDB Entry
tools.cisco.com / security/center/content/CiscoSecurityAdvisory/cisco-sa-20200205-fxnxos-iosxr-cdp-dos
Vendor Advisory