CVE-2021-32643: Http4s core StaticFile.fromUrl Can Leak Presence Of Vulnerability

MODERATE
Advisory Identifier: GHSA-6h7w-fc84-x7p6
CVSS 5.8
CWE-22
Published
Advisory Summary

CVE-2021-32643 is a MODERATE (CVSS 5.8) staticfile.fromurl can leak presence of vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) affecting Http4s core libraries in the Maven ecosystem. The issue involves staticfile.fromurl can leak presence of a directory. Remediation is available by upgrading affected packages to version 0.21.24, 0.22.0-RC1, 0.23.0-RC1, 1.0.0-M23.

CVE-2021-32643 at a Glance

CVE Identifier CVE-2021-32643
GHSA Identifier GHSA-6h7w-fc84-x7p6
Severity MODERATE
CVSS v3.1 Base Score 5.8
CWE Classification CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected Product Http4s core
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2021-32643

To remediate this vulnerability, upgrade all affected Http4s core dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.http4s:http4s-core fixed: 0.21.24
<dependency>
    <groupId>org.http4s</groupId>
    <artifactId>http4s-core</artifactId>
    <version>0.21.24</version>
</dependency>
org.http4s:http4s-core fixed: 0.22.0-RC1
<dependency>
    <groupId>org.http4s</groupId>
    <artifactId>http4s-core</artifactId>
    <version>0.22.0-RC1</version>
</dependency>
org.http4s:http4s-core fixed: 0.23.0-RC1
<dependency>
    <groupId>org.http4s</groupId>
    <artifactId>http4s-core</artifactId>
    <version>0.23.0-RC1</version>
</dependency>
org.http4s:http4s-core fixed: 1.0.0-M23
<dependency>
    <groupId>org.http4s</groupId>
    <artifactId>http4s-core</artifactId>
    <version>1.0.0-M23</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

mvn dependency:tree -Dincludes=org.http4s

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2021-32643, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.http4s

Analyze the terminal output to locate any version of Http4s core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.21.24), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.http4s command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), where the product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. In Http4s core, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact `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 * 1.0.0-M1 through 1.0.0-M22 ### Patches The [patch](https://github.com/http4s/http4s/commit/52e1890665410b4385e37b96bc49c5e3c708e4e9) is available in the following versions: * v0.21.24 * v0.22.0-RC1 * v0.23.0-RC1 * v1.0.0-M23 Note: a previous version of this advisory incorrectly referred to 0.22.0-M9 and 0.23.0-M2. ### Workarounds Don't call `StaticFile.fromUrl` with non-file URLs. ### For more information If you have any questions or comments about this advisory: * Open an issue in [the http4s repository](https://github.com/http4s/http4s) * Disclose further vulnerabilities according to the [http4s security policy](https://github.com/http4s/http4s/blob/main/SECURITY.md)

CVE-2021-32643 Affected Http4s core Versions

4 component(s)
Fixed Versions:
0.21.240.22.0-RC10.23.0-RC11.0.0-M23
Product / Package Ecosystem Affected Versions Fixed Version
org.http4s:http4s-core
Maven
≥ 0.21.7
< 0.21.24
0.21.24
org.http4s:http4s-core
Maven
≥ 0.22.0-M1
< 0.22.0-RC1
0.22.0-RC1
org.http4s:http4s-core
Maven
≥ 0.23.0-M1
< 0.23.0-RC1
All 1 versions
0.23.0-M1
0.23.0-RC1
org.http4s:http4s-core
Maven
≥ 1.0.0-M1
< 1.0.0-M23
1.0.0-M23

References

Frequently Asked Questions

What is CVE-2021-32643?
CVE-2021-32643 is a security vulnerability in Http4s core involving StaticFile.fromUrl can leak presence of a directory under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal').
Which Http4s core versions are affected?
Affected versions include releases prior to 0.21.24, 0.22.0-RC1, 0.23.0-RC1, 1.0.0-M23 across affected packages: org.http4s:http4s-core.
What version fixes CVE-2021-32643?
Upgrading to 0.21.24, 0.22.0-RC1, 0.23.0-RC1, 1.0.0-M23 (or the latest patched release for your respective branch) resolves the vulnerability.
Is http4s-core affected?
Yes, org.http4s:http4s-core is affected in releases prior to 0.21.24, 0.22.0-RC1, 0.23.0-RC1, 1.0.0-M23. Upgrade your dependency to 0.21.24, 0.22.0-RC1, 0.23.0-RC1, 1.0.0-M23 or later.
What is the CVSS score of CVE-2021-32643?
CVE-2021-32643 has a CVSS v3.1 base score of 5.8 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N.
What CWE is associated with CVE-2021-32643?
CVE-2021-32643 is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') (The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.).
How can I check Maven dependencies for CVE-2021-32643?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.http4s'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6h7w-fc84-x7p6",
  "modified" : "2021-05-27T21:17:06Z",
  "published" : "2021-05-28T15:54:39Z",
  "aliases" : [ "CVE-2021-32643" ],
  "summary" : "StaticFile.fromUrl can leak presence of a directory",
  "details" : "### Impact\n\n`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.\n\nThis affects http4s versions:\n* 0.21.7 through 0.21.23\n* 0.22.0-M1 through 0.22.0-M8\n* 0.23.0-M1\n* 1.0.0-M1 through 1.0.0-M22\n\n### Patches\n\nThe [patch](https://github.com/http4s/http4s/commit/52e1890665410b4385e37b96bc49c5e3c708e4e9) is available in the following versions:\n\n* v0.21.24\n* v0.22.0-RC1\n* v0.23.0-RC1\n* v1.0.0-M23\n\nNote: a previous version of this advisory incorrectly referred to 0.22.0-M9 and 0.23.0-M2.\n\n### Workarounds\n\nDon't call `StaticFile.fromUrl` with non-file URLs.\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n* Open an issue in [the http4s repository](https://github.com/http4s/http4s)\n* Disclose further vulnerabilities according to the [http4s security policy](https://github.com/http4s/http4s/blob/main/SECURITY.md)\n",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.21.7"
      }, {
        "fixed" : "0.21.24"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.22.0-M1"
      }, {
        "fixed" : "0.22.0-RC1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.22.0-M8"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.23.0-M1"
      }, {
        "fixed" : "0.23.0-RC1"
      } ]
    } ],
    "versions" : [ "0.23.0-M1" ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.0.0-M1"
      }, {
        "fixed" : "1.0.0-M23"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.0.0-M22"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/http4s/http4s/security/advisories/GHSA-6h7w-fc84-x7p6"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-32643"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/http4s/http4s/commit/52e1890665410b4385e37b96bc49c5e3c708e4e9"
  }, {
    "type" : "WEB",
    "url" : "https://mvnrepository.com/artifact/org.http4s/http4s-core"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-27T21:17:06Z",
    "nvd_published_at" : "2021-05-27T18:15:00Z"
  }
}