Vulnerability

CVE-2020-3566

High· 8.6KEVCVSS8.6EPSS2%

.rules3/5

Cisco IOS XR Software DVMRP Memory Exhaustion 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.

Threat signal

96/100

Severe

Severity

high

CVSS

8.6

EPSS

Active

KEV

CISA KEV — actively exploited

1502d overdue

AffectedCisco — IOS XR

Added to KEV

2021-11-03

Federal patch due (BOD 22-01)

2022-05-03

Required action (CISA verbatim)

Apply updates per vendor instructions.

Vendor advisory + references

https://nvd.nist.gov/vuln/detail/CVE-2020-3566

CISA description: “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.”

CVSS

v3.1Open in FIRST calculator →

8.6/ 10HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Attack VectorNetworkExploitable remotely over the internet — no local access needed.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredNoneUnauthenticated — no credentials needed.
User InteractionNoneFully automated — no victim action needed.
ScopeChangedImpact extends beyond the vulnerable component (e.g. sandbox escape).
Confidentiality ImpactNoneNo confidentiality impact.
Integrity ImpactNoneNo integrity impact.
Availability ImpactHighTotal loss of availability — full DoS possible.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

2.14%

probability of exploitation in next 30 days

p85

higher than 85% of all CVEs

3-day trend↑ 0pp

Mid-pack — moderate exploitation likelihood.

Vendor VEX

No VEX statements published for CVE-2020-3566. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCAct

Active exploitation with total impact on essential/support systems

exploitation: active
automatable: yes
impact: total
mission: support

Lifecycle

2021-11-03Added to CISA KEVransomware: Unknown
2021-11-03Published
2022-05-03Federal patch due (BOD 22-01)
2026-06-12Last modified1 source

No source-event history recorded yet. New revisions will appear here as ingestors re-fetch this CVE.