How severe is CVE-2021-32643?

CVE-2021-32643 has a CVSS score of 5.8/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-32643?

CVE-2021-32643 affects the following packages: org.http4s:http4s-core (Maven), org.http4s:http4s-core (Maven), org.http4s:http4s-core (Maven), org.http4s:http4s-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-32643?

Update org.http4s:http4s-core to 0.21.24 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32643 is resolved across your whole dependency graph.

How do I detect CVE-2021-32643 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.http4s:http4s-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-32643 if there is no patch (or I can't update yet)?

Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Is CVE-2021-32643 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-32643 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-32643?

CVE-2021-32643 has an EPSS (Exploit Prediction Scoring System) score of 1.4%, placing it in the 72th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-32643?

CVE-2021-32643 is classified as Path Traversal (CWE-22). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-32643 published, and has it been updated?

CVE-2021-32643 was published on May 27, 2021 and was last updated on July 9, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

MEDIUM severity

CVE-2021-32643 — http4s-core

MEDIUMFix: http4s/http4s@52e1890

CVE-2021-32643 is a medium-severity (CVSS 5.8) Path Traversal vulnerability in org.http4s:http4s-core. A fix is available for org.http4s:http4s-core — see the affected versions and patch details below.

StaticFile.fromUrl can leak presence of a directory

Also known asGHSA-6h7w-fc84-x7p6

Published

May 27, 2021

Updated

Jul 9, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

None indexed

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs72th percentile — riskier than 72% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-32643 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

4 pkgs affected

☕org.http4s:http4s-core☕org.http4s:http4s-core☕org.http4s:http4s-core☕org.http4s:http4s-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

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 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
Disclose further vulnerabilities according to the http4s security policy

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.http4s:http4s-core`	≥ 0.21.7&&< 0.21.24	0.21.24`org.http4s:http4s-core:0.21.24`
☕Maven	`org.http4s:http4s-core`	≥ 0.22.0-M1&&< 0.22.0-RC1	0.22.0-RC1`org.http4s:http4s-core:0.22.0-RC1`
☕Maven	`org.http4s:http4s-core`	≥ 0.23.0-M1&&< 0.23.0-RC1	0.23.0-RC1`org.http4s:http4s-core:0.23.0-RC1`
☕Maven	`org.http4s:http4s-core`	≥ 1.0.0-M1&&< 1.0.0-M23	1.0.0-M23`org.http4s:http4s-core:1.0.0-M23`

Affected Products

1 product · 32 configurations

Application

http4stypelevel

≥ 0.21.7 && < 0.21.24

3 versions

0.22.00.23.01.0.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.http4s:http4s-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.http4s:http4s-core to 0.21.24 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32643 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Frequently Asked Questions

### 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