CVE-2021-34740

Device reload via WCP packet-buffer leak

Published Sep 23, 2021 · Updated Nov 7, 2024

Denial of service in Cisco Aironet Access Point Software allows physically proximate attackers to force an AP reload via 802.11 frames. The WCP implementation mishandles unexpected frames, leaking packet buffers until allocation failures restart wcpd and reload the access point. The attacker must be within wireless range and needs no authentication; successful exploitation interrupts wireless service through a device reload.

CVSS severity7.4
High
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Cisco Aironet Access Point Software allows physically proximate attackers to force an AP reload via 802.11 frames. The WCP implementation mishandles unexpected frames, leaking packet buffers until allocation failures restart wcpd and reload the access point. The attacker must be within wireless range and needs no authentication; successful exploitation interrupts wireless service through a device reload.

The record

CVE
CVE-2021-34740
Published
Sep 23, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco Aironet Access Point Software
Classifications
CWE-401, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 23, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 7, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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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 Softwareversion=n/a

Published CVSS scores

6.1NIST NVDAV:A/AC:L/Au:N/C:N/I:N/A:C
7.4Cisco Systems, Inc.CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

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-401Missing Release of Memory after Effective Lifetime
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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