CVE-2019-16020Network attack vector

BGP process restart via malformed EVPN attributes

Published Jan 26, 2020 · Updated Nov 15, 2024

Denial of service in Cisco IOS XR Software after 6.6.1 allows remote attackers to restart the BGP process with malformed EVPN updates. The BGP EVPN implementation incorrectly processes crafted attributes in update messages instead of rejecting them, terminating and restarting BGP. Exploitation requires a configured valid BGP peer or injection into an existing peer TCP session, interrupting routing while the process restarts.

CVSS severity8.6
High
EPSS probability1.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Cisco IOS XR Software after 6.6.1 allows remote attackers to restart the BGP process with malformed EVPN updates. The BGP EVPN implementation incorrectly processes crafted attributes in update messages instead of rejecting them, terminating and restarting BGP. Exploitation requires a configured valid BGP peer or injection into an existing peer TCP session, interrupting routing while the process restarts.

The record

CVE
CVE-2019-16020
Published
Jan 26, 2020
Updated
Nov 15, 2024
Vendor
ClamAV
Product
Cisco IOS XR Software
Classifications
CWE-400, CWE-399, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 26, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOS XR Softwareversion=unspecified <n/a

Published CVSS scores

5.0NISTAV:N/AC:L/Au:N/C:N/I:N/A:P
8.6Cisco Systems, Inc.CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
8.6NISTCVSS:3.1/AV:N/AC:L/PR:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-400Uncontrolled Resource Consumption
CWE-399Resource Management Errors
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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