CVE-2024-21631Network attack vector

Host spoofing via 16-bit URI indexes

Published Jan 3, 2024 · Updated Sep 18, 2024

Improper URI parsing in Vapor before 4.90.0 allows remote authenticated users to spoof a validated URL's destination host. vapor_urlparser_parse converts URI component ranges to 16-bit indexes, so an abnormally long zero-padded port wraps the authority boundaries and misparses the host. Exposure requires an application to trust Vapor URI properties when validating attacker-controlled URLs, particularly before forwarding them to an HTTP client.

CVSS severity6.5
Medium
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper URI parsing in Vapor before 4.90.0 allows remote authenticated users to spoof a validated URL's destination host. vapor_urlparser_parse converts URI component ranges to 16-bit indexes, so an abnormally long zero-padded port wraps the authority boundaries and misparses the host. Exposure requires an application to trust Vapor URI properties when validating attacker-controlled URLs, particularly before forwarding them to an HTTP client.

The record

CVE
CVE-2024-21631
Published
Jan 3, 2024
Updated
Sep 18, 2024
Vendor
Vapor
Product
Vapor
Classifications
CWE-1104, CWE-20, CWE-190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 3, 2024CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <4.90.0
  2. Affected versionversion=< 4.90.0
  3. Affected versionversion=pkg:swift/github.com/vapor/vapor@0 <pkg:swift/github.com/vapor/[email protected]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Vapor · Vaporversion=0 <4.90.0; version=< 4.90.0; version=pkg:swift/github.com/vapor/vapor@0 <pkg:swift/github.com/vapor/[email protected]

Published CVSS scores

6.5GitHub CNACVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1104Use of Unmaintained Third Party Components
CWE-20Improper Input Validation
CWE-190Integer Overflow or Wraparound

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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