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CVE-2021-1439

23
FAUCET Score

CVE-2021-1439 is a denial-of-service vulnerability in Cisco Aironet Series Access Points Software, specifically affecting the multicast DNS (mDNS) gateway feature. An unauthenticated, adjacent attacker can exploit insufficient input validation of mDNS traffic by sending a crafted packet, causing the access point to reboot. This vulnerability has a CVSS score of 7.4 (High), indicating a low-complexity attack with high impact on availability, requiring network adjacency. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:cisco:aironet_access_point_software:-:*:*:*:*:*:*:*
>= 17.1, < 17.3.3CPE matchmatch criteria
cpe:2.3:o:cisco:catalyst_9800_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.4HIGH

CVSS:3.1/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
3.1

Exploit Intelligence

EPSS Score
0.39%
Probability of exploitation in next 30 days
EPSS Percentile
31.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0039 is in the 28th percentile among its peer group of 1,875 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.2 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-aironet-mdns-dos-E6KwYuMx
Vendor Advisory