CVE-2025-20340
highpriority · track · 0EPSS 0.006 · 50 %ileDEEUNLRUUSEPSS · scored 2026-10-21
A vulnerability in the Address Resolution Protocol (ARP) implementation of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to trigger a broadcast storm, leading to a denial of service (DoS) condition on an affected device. This vulnerability is due to how Cisco IOS XR Software processes a high, sustained rate of ARP traffic hitting the management interface. Under certain conditions, an attacker could exploit this vulnerability by sending an excessive amount of traffic to the management interface of an affected device, overwhelming its ARP processing capabilities. A successful exploit could result in degraded device performance, loss of management connectivity, and complete unresponsiveness of the system, leading to a DoS condition.
remediations
Vendor fix, mitigation, or workaround guidance, as published by each source.
A vendor fix is available.
- FixedCisco IOS XR Softwarecisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.8–7.4
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (122)
Products and version ranges known to be affected.
advisories (3)
Vendor and ecosystem advisories describing this.
- NCSC-2025-0286Kwetsbaarheden verholpen in Cisco IOS XR SoftwareNL2025-09-11csaf · ncsc_nlNL
Cisco heeft kwetsbaarheden verholpen in Cisco IOS XR Software.
- WID-SEC-W-2025-2032Cisco IOS XR: Mehrere SchwachstellenDeutsch2025-09-10csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Cisco IOS XR ausnutzen, um Sicherheitsvorkehrungen zu umgehen und um einen Denial-of-Service-Zustand zu verursachen.
- cisco-sa-iosxr-arp-storm-EjUU55yMCisco IOS XR ARP Broadcast Storm Denial of Service Vulnerability2025-09-10csaf · cisco_csafUS
A vulnerability in the Address Resolution Protocol (ARP) implementation of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to trigger a broadcast storm, leading to a denial of service (DoS) condition on an affected device. This vulnerability is due to how Cisco IOS XR Software processes a high, sustained rate of ARP traffic hitting the management interface. Under certain conditions, an attacker could exploit this vulnerability by sending an excessive amount of traffic to the management interface of an affected device, overwhelming its ARP processing capabilities. A successful exploit could result in degraded device performance, loss of management connectivity, and complete unresponsiveness of the system, leading to a DoS condition. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is part of the September 2025 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2025 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication ["https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75549"].
also known as (4)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (3)
External citations — patches, advisories, analysis.
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-arp-storm-EjUU55yMcnnvd
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-arp-storm-EjUU55yMenisa_euvd
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-arp-storm-EjUU55yMnvd
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