CVE-2021-34770Network attack vector

Unauthenticated administrative code execution via flawed CAPWAP validation

Published Sep 23, 2021 · Updated Nov 7, 2024

Buffer overflow in CAPWAP processing in Cisco IOS XE Software allows remote attackers to execute administrative code via crafted packets. CAPWAP packet validation applies incorrect logic to crafted fields, allowing packet data to overflow a heap buffer. No authentication or user interaction is required; exploitation grants administrative execution or crashes and reloads the controller.

CVSS severity10.0
Critical
EPSS probability2.96%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in CAPWAP processing in Cisco IOS XE Software allows remote attackers to execute administrative code via crafted packets. CAPWAP packet validation applies incorrect logic to crafted fields, allowing packet data to overflow a heap buffer. No authentication or user interaction is required; exploitation grants administrative execution or crashes and reloads the controller.

The record

CVE
CVE-2021-34770
Published
Sep 23, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco IOS XE Software
Classifications
CWE-122, T1190
Attack vector
network
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?

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  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOS XE Softwareversion=n/a

Published CVSS scores

10.0CiscoCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/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.

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No observations available

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

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
T1190Exploit Public-Facing Application

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

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Your stack

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