CVE-2021-1439

Access-point reboot via crafted mDNS packet

Published Mar 24, 2021 · Updated Nov 8, 2024

Buffer overflow in Cisco Aironet Access Point Software allows attackers to reboot affected access points with crafted mDNS packets. The mDNS gateway performs a buffer copy without adequately validating incoming mDNS packet data or its size. Exposure requires mDNS gateway enablement and either FlexConnect local switching on a wireless network or access through a configured mDNS VLAN; exploitation reboots the access point and interrupts service.

CVSS severity7.4
High
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Buffer overflow in Cisco Aironet Access Point Software allows attackers to reboot affected access points with crafted mDNS packets. The mDNS gateway performs a buffer copy without adequately validating incoming mDNS packet data or its size. Exposure requires mDNS gateway enablement and either FlexConnect local switching on a wireless network or access through a configured mDNS VLAN; exploitation reboots the access point and interrupts service.

The record

CVE
CVE-2021-1439
Published
Mar 24, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco Aironet Access Point Software (IOS XE Controller)
Classifications
CWE-120, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 8, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Aironet Access Point Software (IOS XE Controller)version=n/a

Published CVSS scores

7.4NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
3.3NIST NVDAV:A/AC:L/Au:N/C:N/I:N/A:P
7.4CiscoCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo