CVE-2025-20146: ios xr Input Validation Flaw — Fix

Description

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.

Is your site exposed to CVE-2025-20146?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

8.6

HIGH

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

Weakness Type (CWE)

CWE-20 Improper Input Validation

Affected Products

Vendor	Product	Versions
cisco	ios_xr	All
cisco	ios_xr	All
cisco	ios_xr	All
cisco	ios_xr	All
cisco	ios_xr	All
cisco	ios_xr	All
cisco	ios_xr	All
cisco	ios_xr	All
cisco	ios_xr	All
cisco	ios_xr	All
cisco	ios_xr	All
cisco	asr_9006	All
cisco	asr_9010	All
cisco	asr_9901	All
cisco	asr_9902	All
cisco	asr_9903	All
cisco	asr_9904	All
cisco	asr_9906	All
cisco	asr_9910	All
cisco	asr_9912	All
cisco	asr_9922	All

References

Advisories & Patches

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-multicast-ERMrSvq7

Other References

https://blog.apnic.net/2024/09/02/crafting-endless-as-paths-in-bgp/

Frequently Asked Questions

What is CVE-2025-20146? +

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. It has a CVSS v3.1 base score of 8.6 (HIGH).

How severe is CVE-2025-20146? +

CVE-2025-20146 has a CVSS v3.1 score of 8.6 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-20146? +

CVE-2025-20146 affects products from cisco, specifically: asr_9006, asr_9010, asr_9901, asr_9902, asr_9903, asr_9904, asr_9906, asr_9910, asr_9912, asr_9922, ios_xr. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-20146? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-13826

Zervit's portable HTTP/web server is vulnerable to remote DoS attacks when a configuration reset request is made. The vulnerability is …

CVE-2026-22102

A POST request sent to a specific webserver endpoint can be used to write to arbitrary file locations. The endpoint …

CVE-2024-54011

Penetration Testing engineers at Amazon have discovered a flaw where the camera system fails to properly handle data supplied in …

CVE-2026-62656

A security flaw was found in certain NETGEAR RAX models that could allow a logged-in user to send specially crafted …

CVE-2026-62659

A security flaw was discovered in the NETGEAR WAX333 Access Point that could allow someone already logged in and connected …

CVE-2026-62658

A security flaw was discovered in certain NETGEAR Nighthawk RAX series routers that could allow someone already logged in to …

CVE-2025-20146