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TI-2021-01166 Aliases CVE-2021-1439GHSA-2p9c-p5jq-7j4g

Cisco Aironet Access Points FlexConnect Multicast DNS Denial of Service Vulnerability

Priority LOW 33CWE-120Published · Updated

Key facts

Attack vector
Adjacent network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-120 and the CVSS impact.

Summary

A vulnerability in the multicast DNS (mDNS) gateway feature of Cisco Aironet Series Access Points Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient input validation of incoming mDNS traffic. An attacker could exploit this vulnerability by sending a crafted mDNS packet to an affected device through a wireless network that is configured in FlexConnect local switching mode or through a wired network on a configured mDNS VLAN. A successful exploit could allow the attacker to cause the access point (AP) to reboot, resulting in a DoS condition.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00401 34th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
CiscoCisco Aironet Access Point Software (IOS XE Controller)all versions—No fix listedCNA
  • Cisco Aironet Access Point Software (IOS XE Controller) VendorCisco Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 13

CPEVersionsRoleVendor
cpe:2.3:a:cisco:aironet_access_point_software:-:*:*:*:*:*:*:*not specified by NVDVulnerableCisco
cpe:2.3:h:cisco:1100_integrated_services_router:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:aironet_1540:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:aironet_1560:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:aironet_1800:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:aironet_2800:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:aironet_3800:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:aironet_4800:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:catalyst_9100:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:catalyst_iw6300:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
  • cpe:2.3:a:cisco:aironet_access_point_software:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Cisco
  • cpe:2.3:h:cisco:1100_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:aironet_1540:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:aironet_1560:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:aironet_1800:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:aironet_2800:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:aironet_3800:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:aironet_4800:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:catalyst_9100:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:catalyst_iw6300:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
Show 3 more CPE
CPEVersionsRoleVendor
cpe:2.3:h:cisco:esw6300:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:o:cisco:catalyst_9800_firmware:*:*:*:*:*:*:*:*17.1 to before 17.3.3VulnerableCisco
cpe:2.3:h:cisco:catalyst_9800:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
  • cpe:2.3:h:cisco:esw6300:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:o:cisco:catalyst_9800_firmware:*:*:*:*:*:*:*:* Versions 17.1 to before 17.3.3 Vulnerable ·Cisco
  • cpe:2.3:h:cisco:catalyst_9800:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-1439
  2. 2026-10-03 Alias added: GHSA-2p9c-p5jq-7j4g

References

Advisory 1

  • TI-2018-00197 Improper input validation in Cisco Aironet 1810, 1830, and 1850 Series Access Points CVSS 3.0HIGH 8.6
  • TI-2017-02928 Access control flaw in Cisco Mobility Express 1800 Access Point Series CVSS 3.0CRITICAL 9.8
  • TI-2022-05181 Cisco Embedded Wireless Controller with Catalyst Access Points IP Flood Denial of Service Vulnerability CVSS 3.1HIGH 8.6
  • TI-2020-03104 Cisco Aironet Access Points UDP Flooding Denial of Service Vulnerability CVSS 3.1HIGH 8.6
  • TI-2021-01164 Cisco Aironet Access Points FlexConnect Upgrade Information Disclosure Vulnerability CVSS 3.1HIGH 7.5
  • TI-2020-03103 Cisco Aironet Access Point Authentication Flood Denial of Service Vulnerability CVSS 3.1HIGH 8.6
See all 26 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences