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CVE-2020-3399

21
FAUCET Score

CVE-2020-3399 describes a denial-of-service vulnerability in Cisco IOS XE Software for Catalyst 9800 Series Wireless Controllers, stemming from insufficient input validation in the CAPWAP protocol. An unauthenticated, remote attacker can exploit this by sending a crafted CAPWAP packet, leading to a buffer over-read that causes the device to crash and reload. With a CVSS score of 8.6 (High), this vulnerability has a network attack vector and low attack complexity, posing a significant availability risk. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
16.12CPE matchmatch criteria
cpe:2.3:o:cisco:ios_xe:16.12:*:*:*:*:*:*:*
16.12.1sCPE matchmatch criteria
cpe:2.3:o:cisco:ios_xe:16.12.1s:*:*:*:*:*:*:*
16.12.2CPE matchmatch criteria
cpe:2.3:o:cisco:ios_xe:16.12.2:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.6HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
4.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.36%
Probability of exploitation in next 30 days
EPSS Percentile
68.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0136 is in the 49th percentile among its peer group of 51,551 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

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

tools.cisco.com / security/center/content/CiscoSecurityAdvisory/cisco-sa-capwap-dos-ShFzXf
Vendor Advisory