CVE-2021-1493Network attack vector

Data disclosure and reload via unchecked HTTP input

Published Apr 29, 2021 · Updated Nov 8, 2024

Buffer overflow in Cisco Adaptive Security Appliance Software allows remote authenticated users to disclose data or reload the device. The web services interface applies insufficient boundary checks to specific data in a malicious HTTP request, allowing the input to overrun a buffer. Exposure requires a vulnerable release with AnyConnect IKEv2 client services, AnyConnect SSL VPN, or Clientless SSL VPN enabled; consequences are limited to data fragments and a service-interrupting reload.

CVSS severity8.5
High
EPSS probability1.20%
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 Cisco Adaptive Security Appliance Software allows remote authenticated users to disclose data or reload the device. The web services interface applies insufficient boundary checks to specific data in a malicious HTTP request, allowing the input to overrun a buffer. Exposure requires a vulnerable release with AnyConnect IKEv2 client services, AnyConnect SSL VPN, or Clientless SSL VPN enabled; consequences are limited to data fragments and a service-interrupting reload.

The record

CVE
CVE-2021-1493
Published
Apr 29, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco Adaptive Security Appliance (ASA) Software
Classifications
CWE-120, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 29, 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

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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 privilegesauthenticated

What is affected?

ClamAV · Cisco Adaptive Security Appliance (ASA) Softwareversion=n/a

Published CVSS scores

7.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H
7.5NIST NVDAV:N/AC:L/Au:S/C:P/I:N/A:C
8.5Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/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.

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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
Privilegesauthenticated
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

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Your stack

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