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CVE Record

CVE-2020-3201: Cisco IOS and IOS XE Software Tcl Denial of Service Vulnerability

A vulnerability in the Tool Command Language (Tcl) interpreter of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, local attacker with privileged EXEC credentials to cause a denial of service (DoS) condition on an affected system. The vulnerability is due to insufficient input validation of data passed to the Tcl interpreter. An attacker could exploit this vulnerability by executing crafted Tcl arguments on an affected device. An exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

MediumCVSS 6Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This issue can let a highly privileged local user crash and reload an affected Cisco IOS or IOS XE device through malformed Tcl interpreter input. Business impact is service interruption, not data theft. The attacker already needs privileged EXEC access, so urgency depends on who can administer affected network devices.

Executive priority

Treat as a targeted availability risk for network infrastructure. Prioritize externally critical or business-critical devices, especially where privileged administrator access is broadly assigned or weakly controlled.

Technical view

CVE-2020-3201 is an insufficient input validation flaw in the Tcl interpreter in Cisco IOS and IOS XE Software. With privileged EXEC credentials and local access, an attacker could pass crafted Tcl arguments that cause the device to reload, producing a denial of service. CVSS v3.0 score is 6.0.

Likely exposure

Exposure appears limited to Cisco IOS or IOS XE devices where an attacker can obtain privileged EXEC access. The source bundle names Cisco IOS 12.2(25)S and references Cisco’s advisory for product-specific status.

Exploitation context

The provided sources do not show CISA KEV listing or active exploitation. Exploitation requires authenticated local access with high privileges, reducing broad internet-driven risk but making compromised admin accounts or insider misuse relevant.

Researcher notes

The key control point is privilege. Validate affected software against Cisco’s advisory and focus review on Tcl interpreter handling, reload telemetry, AAA logs, and privileged access paths. The source bundle does not provide exploit evidence or detailed fixed-version data.

Mitigation direction

  • Check Cisco’s advisory for affected and fixed releases before choosing an upgrade path.
  • Upgrade or remediate affected devices according to Cisco guidance.
  • Restrict privileged EXEC access to trusted administrators only.
  • Enforce strong AAA controls and remove unnecessary privileged accounts.
  • Monitor affected devices for unexpected reloads and administrative Tcl activity.

Validation and detection

  • Inventory Cisco IOS and IOS XE devices and record exact software releases.
  • Compare device releases with Cisco’s CVE-2020-3201 advisory.
  • Confirm who has privileged EXEC access on potentially affected devices.
  • Review logs for unexpected reloads near privileged administrative sessions.
  • Document compensating controls where immediate upgrade guidance is pending.
Prepared
Confidence
medium
Sources
3

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-20: Exact CWE lookup

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cve · low confidence lookup

CVE-2020-3201 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
6 (3.0)
Known Exploited
No
Published

Vector: CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
6CVSS 3.0MediumCVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H1.54Primary CVE score

Vulnerability scoring details

Base CVSS 3.0 score

6Medium
CVSS 3.0 vector shape for CVE-2020-3201Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
CiscoCisco IOS 12.2(25)Sn/aListed
Weakness

CWE details

CWE-20

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.