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

What is CVE-2021-32643?

CVE-2021-32643 is a medium-severity vulnerability in http4s, published on 27 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-22

Which versions are affected by CVE-2021-32643?

8 open source packages ship an affected version, including org.http4s:http4s-core. It affects 1 product.

Products include Typelevel Http4s.

How do I fix CVE-2021-32643?

Upgrade org.http4s:http4s-core to a fixed version for your release line: 0.21.24, 0.22.0-RC1, 0.23.0-RC1 or 1.0.0-M23.

Is CVE-2021-32643 being exploited?

There is no known exploitation of CVE-2021-32643 in the wild and no public exploit code.

Other vulnerabilities in http4s

• CVE-2021-39185 Default CORS config allows any origin with credentials Critical 9.1
• CVE-2021-41084 Response Splitting from unsanitized headers in http4s High 8.7
• CVE-2020-5280 Local file inclusion vulnerability in http4s High 7.6
• CVE-2023-22465 Http4s has fatal error parsing User-Agent and Server headers High 7.5
• CVE-2021-21294 Unbounded connection acceptance in http4s-blaze-server High 7.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-6h7w-fc84-x7p6.