CVE-2020-3201

Reload DoS via crafted Tcl arguments

Published Jun 3, 2020 · Updated Nov 15, 2024

Improper input validation in the Tcl interpreter in Cisco IOS allows local users to cause device reloads and denial of service via crafted Tcl arguments. The interpreter processes attacker-supplied Tcl arguments without sufficient validation, allowing a malformed command to trigger a reload. Tcl shell access normally requires privilege level 15, although custom privilege mappings can lower that gate; successful exploitation interrupts device availability.

CVSS severity6.5
Medium
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in the Tcl interpreter in Cisco IOS allows local users to cause device reloads and denial of service via crafted Tcl arguments. The interpreter processes attacker-supplied Tcl arguments without sufficient validation, allowing a malformed command to trigger a reload. Tcl shell access normally requires privilege level 15, although custom privilege mappings can lower that gate; successful exploitation interrupts device availability.

The record

CVE
CVE-2020-3201
Published
Jun 3, 2020
Updated
Nov 15, 2024
Vendor
ClamAV
Product
Cisco IOS
Classifications
CWE-20, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 3, 2020CVE publishedPublication date reported by the CVE source.
  2. Nov 15, 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 vectorlocal
Required privilegesauthenticated

What is affected?

ClamAV · Cisco IOSversion=n/a

Published CVSS scores

5.0NVDAV:L/AC:L/Au:N/C:N/I:N/A:C
6.5Cisco Systems, Inc.CVSS:3.1/AV:L/AC:L/PR:L/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.

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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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1499Endpoint Denial of Service

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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