CVE-2025-20146 | Cisco IOS XR Software for ASR 9000 Series Routers Layer 3 Multicast Routing Denial of Service Vulnerability

A vulnerability in the Layer 3 multicast feature of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers, ASR 9902 Compact High-Performance Routers, and ASR 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cause a line card to reset, resulting in a denial of service (DoS) condition. This vulnerability is due to the incorrect handling of malformed IPv4 multicast packets that are received on line cards where the interface has either an IPv4 access control list (ACL) or a QoS policy applied. An attacker could exploit this vulnerability by sending crafted IPv4 multicast packets through an affected device. A successful exploit could allow the attacker to cause line card exceptions or a hard reset. Traffic over that line card would be lost while the line card reloads.

Published: 2025-03-12 Last update: 2025-08-01 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-20146 is rated Moderate Risk (60.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.96%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-20146

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-29 1.25% 0.96% -0.29%
2 2026-04-25 0.88% 1.25% +0.37%
3 2026-04-20 — 0.88% —

Full EPSS history (22 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-20146

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.6 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 4.0 [email protected]

Weakness enumeration for CVE-2025-20146

Affected software / configurations for CVE-2025-20146

Vendor Product Version Raw CPE
cisco ios_xr 7.9.21 cpe:2.3:o:cisco:ios_xr:7.9.21:*:*:*:*:*:*:*
cisco ios_xr 7.10.2 cpe:2.3:o:cisco:ios_xr:7.10.2:*:*:*:*:*:*:*
cisco ios_xr 7.11.1 cpe:2.3:o:cisco:ios_xr:7.11.1:*:*:*:*:*:*:*
cisco ios_xr 7.11.2 cpe:2.3:o:cisco:ios_xr:7.11.2:*:*:*:*:*:*:*
cisco ios_xr 7.11.21 cpe:2.3:o:cisco:ios_xr:7.11.21:*:*:*:*:*:*:*
cisco ios_xr 24.1.1 cpe:2.3:o:cisco:ios_xr:24.1.1:*:*:*:*:*:*:*
cisco ios_xr 24.1.2 cpe:2.3:o:cisco:ios_xr:24.1.2:*:*:*:*:*:*:*
cisco ios_xr 24.2.1 cpe:2.3:o:cisco:ios_xr:24.2.1:*:*:*:*:*:*:*
cisco ios_xr 24.2.2 cpe:2.3:o:cisco:ios_xr:24.2.2:*:*:*:*:*:*:*
cisco ios_xr 24.3.1 cpe:2.3:o:cisco:ios_xr:24.3.1:*:*:*:*:*:*:*
cisco ios_xr 24.3.2 cpe:2.3:o:cisco:ios_xr:24.3.2:*:*:*:*:*:*:*

References for CVE-2025-20146

cvelogic Threat Intelligence