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NVD / CVE Program· CNA GitHub_M

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

Noroxi assessment

Priority: Monitor (action score 23/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.3% (FIRST EPSS); higher than 72.5% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: org.http4s:http4s-core (Maven) 0.21.24, 0.22.0-RC1, 0.23.0-RC1.

Low priority for now. Upgrade to org.http4s:http4s-core (Maven) 0.21.24, 0.22.0-RC1, 0.23.0-RC1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.8 · v3.1—No exploit Fix available
Published
May 27, 2021
Updated
Jun 16, 2026
EPSS
1.3% · 72th percentile

Report tools

JSON

Action score

23

Monitor

Low priority for now.

CVSS
23 / 40 · 5.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.3%

CNA vs NVD score

NVD
5.8
CNA · GitHub_M
5.8
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
typelevelhttp4s

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • typelevel http4s0.21.7 and later · before 0.21.24
  • typelevel http4s0.22.0
  • typelevel http4s0.23.0
  • typelevel http4s1.0.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • http4s http4s

    • >= 0.21.7, < 0.21.24, >= 0.22.0-M1, <= 0.22.0-M8, = 0.23.0-M1, >= 1.0.0-M1, < 1.0.0-M23affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Mavenorg.http4s:http4s-corefrom 0.21.7 · before 0.21.240.21.24
Mavenorg.http4s:http4s-corefrom 0.22.0-M1 · before 0.22.0-RC10.22.0-RC1
Mavenorg.http4s:http4s-corefrom 0.23.0-M1 · before 0.23.0-RC10.23.0-RC1
Mavenorg.http4s:http4s-corefrom 1.0.0-M1 · before 1.0.0-M231.0.0-M23

Same product

typelevel: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-39185Default CORS config allows any origin with credentials
    36Monitor
  • CVE-2020-5280Local file inclusion vulnerability in http4s
    32Monitor
  • CVE-2021-21294Unbounded connection acceptance in http4s-blaze-server
    31Monitor

Published before and after this one in the same product

  • Later →CVE-2021-41084Sep 21, 2021 · Response Splitting from unsanitized headers in http4s
    18Monitor
  • Later →CVE-2023-22465Jan 4, 2023 · Http4s has fatal error parsing User-Agent and Server headers
    21Monitor
  • Later →CVE-2025-59822Sep 23, 2025 · Http4s vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section
    25Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Maven:org.http4s:http4s-core0.21.24Package registry (OSV)
Maven:org.http4s:http4s-core0.22.0-RC1Package registry (OSV)
Maven:org.http4s:http4s-core0.23.0-RC1Package registry (OSV)
Maven:org.http4s:http4s-core1.0.0-M23Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
none
Availability
none

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality impact
Low
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N

nvd-primary

Root cause

A user-supplied file name is joined with the allowed directory, but the result is never checked to confirm it is still inside that directory.

The bug in code

The whole CWE-22 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
const file = path.join(ROOT, req.query.name);res.sendFile(file);

Fixed

ts
const file = path.resolve(ROOT, req.query.name);if (!file.startsWith(ROOT + path.sep)) {  return res.sendStatus(400);}res.sendFile(file);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records