How severe is CVE-2020-3566?

CVE-2020-3566 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-3566 being actively exploited?

Yes. CVE-2020-3566 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2021-11-03, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2020-3566?

CVE-2020-3566 affects Cisco Ios Xr. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-3566?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2020-3566 have an EU (EUVD) identifier?

Yes. CVE-2020-3566 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2020-24837. It is also flagged as exploited in the EUVD (since 2021-11-03).

When was CVE-2020-3566 published?

CVE-2020-3566 was published on 2020-08-29 and last updated on 2026-06-17.

CVE-2020-3566

CVE-2020-3566 is a high-severity vulnerability in Cisco Ios Xr with a CVSS 3.x base score of 8.6. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2021-11-03). The underlying weakness is classified as CWE-770.

Key facts

Severity: High (CVSS 3.x base score 8.6)
CVSS v2: 7.8
EPSS exploit prediction: 4% (89th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2021-11-03)
EU (EUVD) id: EUVD-2020-24837
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2021-11-03)
Weakness: CWE-770
Affected product: Cisco Ios Xr
Published: 2020-08-29
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-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 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.
How severe is CVE-2020-3566?: CVE-2020-3566 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-3566 being actively exploited?: Yes. CVE-2020-3566 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2021-11-03, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2020-3566?: CVE-2020-3566 affects Cisco Ios Xr. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-3566?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2020-3566 have an EU (EUVD) identifier?: Yes. CVE-2020-3566 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2020-24837. It is also flagged as exploited in the EUVD (since 2021-11-03).
When was CVE-2020-3566 published?: CVE-2020-3566 was published on 2020-08-29 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:cisco:ios_xr:6.4.2:*:*:*:*:*:*:*

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