CVE-2021-1439

lowpriority · track · 30EPSS 0.004 · 34 %ileEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.40% (34th) EPSS

CVSS 3.3 · low

Is it mine?

12 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · fstec_bdu · cisco_csaf

EPSS · scored 2026-10-27

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.

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

FixedCisco Aironet Access Point Software (IOS XE Controller)cisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com

cvss

Technical severity, 0–10. One row per scoring source.

7.4

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–high · 3.3–7.4

v2.03.3lowAV:A/AC:L/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 6.5 · impact 2.9

v3.17.4highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 2.8 · impact 4

v3.17.4highAV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU

v3.17.4highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · ENISA EU

v3.17.4highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · psirt@cisco.com USexploitability 2.8 · impact 4

v3.16.8mediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

v3.17.4highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · Cisco PSIRT US

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-120USCWE-120US

affected products (12)

Products and version ranges known to be affected.

Cisco Cisco Aironet Access Point Software (IOS XE Controller)all versionscisco_csafUS
Cisco Cisco Aironet Access Point Software (IOS XE Controller)≤ n/aenisa_euvdEU
Cisco Systems Inc. Catalyst 9100all versionsfstec_bduRU
Cisco Systems Inc. Catalyst IW 6300all versionsfstec_bduRU
Cisco Systems Inc. Cisco Aironet 1540all versionsfstec_bduRU
Cisco Systems Inc. Cisco Aironet 1560all versionsfstec_bduRU
Cisco Systems Inc. Cisco Aironet 1800all versionsfstec_bduRU
Cisco Systems Inc. Cisco Aironet 2800all versionsfstec_bduRU
Cisco Systems Inc. Cisco Aironet 3800all versionsfstec_bduRU
Cisco Systems Inc. Cisco Aironet 4800all versionsfstec_bduRU
cisco aironet access point softwareall versionsnvdUScpe:2.3:a:cisco:aironet_access_point_software:*:*:*:*:*:*:*:*
cisco catalyst 9800 firmware17.1 → 17.3.3nvdUScpe:2.3:o:cisco:catalyst_9800_firmware:*:*:*:*:*:*:*:*

advisories (1)

Vendor and ecosystem advisories describing this.

cisco-sa-aironet-mdns-dos-E6KwYuMxCisco Aironet Access Points FlexConnect Multicast DNS Denial of Service Vulnerability2021-03-24csaf · cisco_csafUS
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. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cisco_csaf nvd NVD CVE.org MITRE

published 2021-03-24modified 2026-06-17

references (5)

External citations — patches, advisories, analysis.

scry

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