CVE-2020-3566

8.6 HIGH 4% exploit odds exploited in the wild Fix listed Denial of service OS & kernel

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of service disruption.
In the wild: CISA lists this as exploited in real attacks. Treat as urgent.
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2019-12-12 00:00 UTC ReservedThe CVE id was reserved by its CNA
2020-08-29 16:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2021-11-03 Exploited in the wildAdded to CISA's Known Exploited Vulnerabilities list
2022-05-03 Remediation deadlineCISA's due date for federal agencies to fix it
2026-06-17 03:18 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: yes, CISA lists it. This puts it above everything that is not.
Exploit odds: 3.7% in the next 30 days (EPSS).
Severity: 8.6 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2020-08-29 16:15 UTC
Last modified: 2026-06-17 03:18 UTC
Added to CISA KEV: 2021-11-03
Exploit probability: 3.7% · EPSS, next 30 days
Weakness: CWE-400 · Uncontrolled resource consumption
Record status: Analyzed

Affected

Cisco iOS Xr 6.4.2

Attack profile CVSS 3.1 · 8.6

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Changed
Confidentiality: None
Integrity: None
Availability: High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Is it in your code?

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Fix and advisories

References

NVD record · CVE.org record