CVE-2021-1581Network attack vector

Upload-partition exhaustion via unauthenticated file upload

Published Aug 25, 2021 · Updated Nov 7, 2024

Improper access control in Cisco APIC allows remote attackers to upload files through an API endpoint and fill the upload partition. The specific API endpoint accepts file uploads without enforcing authentication or authorization, permitting repeated writes to exhaust its storage. No credentials or user interaction are required; the resulting partition exhaustion degrades availability without reported data disclosure.

CVSS severity6.5
Medium
EPSS probability1.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Cisco APIC allows remote attackers to upload files through an API endpoint and fill the upload partition. The specific API endpoint accepts file uploads without enforcing authentication or authorization, permitting repeated writes to exhaust its storage. No credentials or user interaction are required; the resulting partition exhaustion degrades availability without reported data disclosure.

The record

CVE
CVE-2021-1581
Published
Aug 25, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco Application Policy Infrastructure Controller (APIC)
Classifications
CWE-284, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 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 vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Application Policy Infrastructure Controller (APIC)version=n/a

Published CVSS scores

6.5CiscoCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L/E:X/RL:X/RC:X
6.4NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:P
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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.

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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-284Improper Access Control
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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