CVE-2021-1440Network attack vector

BGP process crash via malformed RTR header

Published Nov 18, 2024 · Updated Nov 18, 2024

Denial of service in Cisco IOS XR Software allows remote attackers to crash and repeatedly restart the BGP process with a crafted RTR packet. The RPKI implementation incorrectly handles a specific RPKI-to-Router Protocol packet header received over an established RTR TCP connection, triggering the process failure. Exploitation requires RPKI to be configured and in use, plus control of the configured validator or a man-in-the-middle position; the resulting restarts destabilize BGP routing.

CVSS severity6.8
Medium
EPSS probability0.80%
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 allows remote attackers to crash and repeatedly restart the BGP process with a crafted RTR packet. The RPKI implementation incorrectly handles a specific RPKI-to-Router Protocol packet header received over an established RTR TCP connection, triggering the process failure. Exploitation requires RPKI to be configured and in use, plus control of the configured validator or a man-in-the-middle position; the resulting restarts destabilize BGP routing.

The record

CVE
CVE-2021-1440
Published
Nov 18, 2024
Updated
Nov 18, 2024
Vendor
ClamAV
Product
Cisco IOS XR Software
Classifications
CWE-617, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 18, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 18, 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=6.5.1
  2. Affected versionversion=6.5.2
  3. Affected versionversion=6.5.3
  4. Affected versionversion=6.6.1
  5. Affected versionversion=6.6.11
  6. Affected versionversion=6.6.12
  7. Affected versionversion=6.6.2
  8. Affected versionversion=6.6.25
  9. Affected versionversion=6.6.3
  10. Affected versionversion=6.6.4
  11. Affected versionversion=7.0.1
  12. Affected versionversion=7.0.11
  13. Affected versionversion=7.0.12
  14. Affected versionversion=7.0.14
  15. Affected versionversion=7.0.2
  16. Affected versionversion=7.0.90
  17. Affected versionversion=7.1.1
  18. Affected versionversion=7.1.2
  19. Affected versionversion=7.2.1
  20. Affected versionversion=7.2.12
  21. Affected versionversion=7.2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOS XR Softwareversion=6.5.1; version=6.5.2; version=6.5.3; version=6.6.1; version=6.6.11; version=6.6.12; version=6.6.2; version=6.6.25; version=6.6.3; version=6.6.4; version=7.0.1; version=7.0.11; version=7.0.12; version=7.0.14; version=7.0.2; version=7.0.90; version=7.1.1; version=7.1.2; version=7.2.1; version=7.2.12; version=7.2.2

Published CVSS scores

6.8Cisco Systems, Inc.CVSS:3.1/AV:N/AC:H/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-617Reachable Assertion
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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