CVE-2018-0136: n/a Cisco Aggregation Services Router 9000 Series…

CVE-2018-0136: A vulnerability in the IPv6 subsystem of Cisco IOS XR Software Release 5.3.4 for the Cisco Aggregation Serv...

A vulnerability in the IPv6 subsystem of Cisco IOS XR Software Release 5.3.4 for the Cisco Aggregation Services Router (ASR) 9000 Series could allow an unauthenticated, remote attacker to trigger a reload of one or more Trident-based line cards, resulting in a denial of service (DoS) condition. The vulnerability is due to incorrect handling of IPv6 packets with a fragment header extension. An attacker could exploit this vulnerability by sending IPv6 packets designed to trigger the issue either to or through the Trident-based line card. A successful exploit could allow the attacker to trigger a reload of Trident-based line cards, resulting in a DoS during the period of time the line card takes to restart. This vulnerability affects Cisco Aggregation Services Router (ASR) 9000 Series when the following conditions are met: The router is running Cisco IOS XR Software Release 5.3.4, and the router has installed Trident-based line cards that have IPv6 configured. A software maintenance upgrade (SMU) has been made available that addresses this vulnerability. The fix has also been incorporated into service pack 7 for Cisco IOS XR Software Release 5.3.4. Cisco Bug IDs: CSCvg46800.

UnknownCVSS not scoredNot KEV-listedUpdatedDec 2, 2024, 21:24 UTC (UTC+00:00)

Security readout for executives and security teams

This Cisco router flaw can let a remote unauthenticated attacker force affected ASR 9000 Trident-based line cards to reload, creating a temporary denial of service. Exposure is narrow: IOS XR 5.3.4, Trident-based line cards, and IPv6 configured. Organizations are likely exposed only if they operate Cisco ASR 9000 routers on IOS XR 5.3.4 with Trident-based line cards carrying IPv6 traffic. Other platforms, releases, or line card families are not identified in the provided sources. Prioritize affected internet-facing or transit ASR 9000 routers because disruption could affect customer or business connectivity. Scope should be fast to determine, and the vendor has named fixed update paths. Mitigation focus: Apply Cisco's available SMU for this vulnerability.; Upgrade to IOS XR 5.3.4 service pack 7 or later fixed guidance.; Confirm affected routers have IPv6 exposure reviewed by network owners..

Prepared: Jun 7, 2026, 20:58 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

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Vulnerability profileCVE Program record

Severity: Unknown
CVSS: Not scored
Known Exploited: No
Published: Jan 31, 2018, 20:00 UTC (UTC+00:00)

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

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2Source links

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Source materials

CVE List V5 sourceCVE List V5
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180131-ipv6CVE reference · x_refsource_CONFIRM

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus

n/aCisco Aggregation Services Router 9000 SeriesCisco Aggregation Services Router 9000 SeriesListed

Weakness

CWE details

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