CVE-2020-3566
8.6, high Known exploitedCisco IOS XR Software DVMRP Memory Exhaustion Vulnerability
- CVSS
- 8.6, high high CVSS v3.1
- EPSS, next 30 days
- 4% higher than 89.5% of scored CVEs
- Exploitation
- Confirmed in the wild
- Published
- 29 Aug 20206 years ago
Known exploited
CISA added this to the Known Exploited Vulnerabilities Catalog on 3 Nov 2021. US federal agencies had to remediate by 3 May 2022, a deadline that has passed.
Required action. Apply updates per vendor instructions.
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.
Details
- Vendor
- Cisco
- Product
- Cisco IOS XR Software
- Weakness
- CWE-400 (opens in a new tab)
- Status
- Analyzed
- Updated
- 17 Jun 2026
- Assigner
- psirt@cisco.com
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
References 2
The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.
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Beyond this page
Is CVE-2020-3566 in your network?
This page tells you how dangerous CVE-2020-3566 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.
CVE-2020-3566 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.
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Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.
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Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.