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Vulnerabilities

Vulnerability · CVE-2020-3566

Cisco IOS XR Software DVMRP Memory Exhaustion Vulnerability

Published Aug 29, 2020 · catalog updated Jun 16, 2026 · Cisco IOS XR

Patch now

CVE-2020-3566 is in the CISA known-exploited catalog, due May 3, 2022. Confirm Cisco IOS XR against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Severity
High8.6
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
3.70%
Remediation
Remediation guidance
Affected products
cpe cisco/ios xr · vendor Cisco IOS XR

A vulnerability in the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to exhaust process memory of an affected device. The vulnerability is due to insufficient queue management for Internet Group Management Protocol (IGMP) packets. An attacker could exploit this vulnerability by sending crafted IGMP traffic to an affected device. A successful exploit could allow the attacker to cause memory exhaustion, resulting in instability of other processes. These processes may include, but are not limited to, interior and exterior routing protocols. Cisco will release software updates that address this vulnerability.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe cisco/ios xr6.4.2
  • vendor Cisco IOS XRversion unspecified

How to fix CVE-2020-3566

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2020-3566 is in the CISA known-exploited catalog, due May 3, 2022. Confirm Cisco IOS XR against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with cisco/ios xr 6.4.2. Apply updates per vendor instructions.

What should an analyst verify?

CWE-400: Uncontrolled Resource Consumption; CWE-770: Allocation of Resources Without Limits or Throttling. EPSS 3.70%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Cisco security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Aug 29, 2020 · Catalog

    Detected

    A vulnerability in the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to exhaust process memory of an affected device. The vulnerability is due to insufficient queue management for Internet Group Management Protocol (IGMP) packets. An attacker could exploit this vulnerability by sending crafted IGMP traffic to an

  2. Nov 3, 2021 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. May 3, 2022 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    A vulnerability in the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to exhaust process memory of an affected device. The vulnerability is due to insufficient queue management for Internet Group Management Protocol (IGMP) packets. An attacker could exploit this vulnerability by sending crafted IGMP traffic to an

Sources

  • CISA KEVConfirmed exploitationCVE-2020-3566

    Cisco IOS XR Distance Vector Multicast Routing Protocol (DVMRP) incorrectly handles Internet Group Management Protocol (IGMP) packets. Exploitation could allow an unauthenticated, remote attacker to immediately crash the IGMP process or make it consume available memory and eventually crash.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2020-3566

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2020-3566

    30-day exploitation probability 3.7%

    first.org
  • NIST NVDVulnerability recordCVE-2020-3566

    A vulnerability in the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to exhaust process memory of an affected device. The vulnerability is due to insufficient queue management for Internet Group

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2020-3566

    Cisco IOS XR Distance Vector Multicast Routing Protocol (DVMRP) incorrectly handles Internet Group Management Protocol (IGMP) packets. Exploitation could allow an unauthenticated, remote attacker to immediately crash the IGMP process or make it consume available memory and eventu

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.