CVE-2020-3199

Guest OS interruption via exposed emulated interface

Published Jun 3, 2020 · Updated Nov 15, 2024

Improper isolation in Cisco IOS on 809, 829, and CGR1000 routers allows adjacent attackers to interrupt the Guest OS. The ingress packet processor accepts external traffic for an internal emulated interface when packets target 127.0.0.0/8. The Guest OS must be running; successful packets can shut down, reload, or uninstall that instance without disclosing data.

CVSS severity8.1
High
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper isolation in Cisco IOS on 809, 829, and CGR1000 routers allows adjacent attackers to interrupt the Guest OS. The ingress packet processor accepts external traffic for an internal emulated interface when packets target 127.0.0.0/8. The Guest OS must be running; successful packets can shut down, reload, or uninstall that instance without disclosing data.

The record

CVE
CVE-2020-3199
Published
Jun 3, 2020
Updated
Nov 15, 2024
Vendor
ClamAV
Product
Cisco IOS
Classifications
CWE-20, T1499
Attack vector
adjacent
Privileges
unauthenticated

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 vectoradjacent
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOSversion=n/a

Published CVSS scores

8.1CiscoCVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:N/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)
Vectoradjacent
Privilegesunauthenticated
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.

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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