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.
- Vendor
- Cisco
- Product
- IOS XR
- CVSS
- 8.6
- EPSS (exploit probability)
- 3.7%
- Status
- kev
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2020-3566 being exploited?
Yes. CISA added CVE-2020-3566 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 3.7% (scored October 14, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ — ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-11-13. Full cross-catalog view: /kev-comparison
CVE-2020-3566 timeline
Every event links to its source. Catalog dates are each catalog's own; day offsets count from NVD publication. Data: JSON
What to do
CISA required actionApply updates per vendor instructions.
US federal civilian agencies must remediate by (181 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Cisco IOS XR CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2022-20821 Cisco IOS XR Open Port Vulnerability | [ MEDIUM ] | 6.5 | 11.5% | |
| CVE-2010-3035 Cisco IOS XR Border Gateway Protocol (BGP) Denial-of-Service Vulnerability | [ HIGH ] | 7.5 | 5.7% | |
| CVE-2009-2055 Cisco IOS XR Border Gateway Protocol (BGP) Denial-of-Service Vulnerability | [ MEDIUM ] | 5.9 | 3.3% | |
| CVE-2020-3569 Cisco IOS XR Software DVMRP Memory Exhaustion Vulnerability | [ HIGH ] | 8.6 | 3.3% | |
| CVE-2020-3118 Cisco IOS XR Software Discovery Protocol Format String Vulnerability | [ HIGH ] | 8.8 | 11.7% |