VulnTideExploited vulnerabilities, by vendor. Data as of .
Known exploitedIn CISA's KEV catalog since Ransomware use: unknown
Cisco IOS XR

CVE-2020-3566: Cisco IOS XR Software DVMRP Memory Exhaustion Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on , 431 days after the CVE record was published.

How likely is exploitation in the next 30 days?
3.7%

EPSS score, percentile 89.7 of all scored records

How severe?
8.6 High

CVSS v3.1 base score, given by the CNA

What should I do?

CISA deadline . Apply updates per vendor instructions.

Advisories and patches (1)

Which versions are affected?

Affected

  • unspecified

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

What to do

Required action, set by CISA

Apply updates per vendor instructions.

CISA due date for this action: .

Advisories and patches

Linked from CISA's catalog entry

Affected products and versions

As listed in the CVE record.

Cisco Cisco IOS XR Software
StatusVersions
Affectedunspecified

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

About this vulnerability

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.

Summary: CISA's KEV catalog, as of .

  • CISA added CVE-2020-3566 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Nov 2021.
  • CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
  • The due date CISA sets for the required action is 3 May 2022.
  • The CVE record was published on 29 Aug 2020, 431 days before it was added to KEV.
  • The CVE record carries a CVSS v3.1 base score of 8.6 (High), given by its CNA.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 3.7% (percentile 89.7), as of 28 Oct 2026.
  • CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact partial.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.

Description

Cisco IOS XR Software DVMRP Memory Exhaustion Vulnerability

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.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

Weakness

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

DateEvent
CVE record published
Added to CISA KEV
CISA due date for the required action
CVE record last updated

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