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TI-2021-04428 Aliases CVE-2021-21328GHSA-gcj9-jj38-hwmc

Denial of service in vapor

Priority LOW 28CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-400.

Summary

Vapor is a web framework for Swift. In Vapor before version 4.40.1, there is a DoS attack against anyone who Bootstraps a metrics backend for their Vapor app. The following is the attack vector: 1. send unlimited requests against a vapor instance with different paths. this will create unlimited counters and timers, which will eventually drain the system. 2. downstream services might suffer from this attack as well by being spammed with error paths. This has been patched in 4.40.1. The `DefaultResponder` will rewrite any undefined route paths for to `vapor_route_undefined` to avoid unlimited counters.

Why it matters now

EPSS 0.01837 79th percentileScored 2026-11-07
Fix Fixed github.com/vapor/vapor (SwiftURL): 4.40.1

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
vaporvaporup to 4.40.0—No fix listedCNA
—github.com/vapor/vapor (SwiftURL)before 4.40.14.40.1Patch availableGHSA-gcj9-jj38-hwmc
  • vapor Vendorvapor Affected up to 4.40.0 Fixed in — No fix listed CNA
  • github.com/vapor/vapor (SwiftURL) Vendor— Affected before 4.40.1 Fixed in 4.40.1 Patch available GHSA-gcj9-jj38-hwmc

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:vapor_project:vapor:*:*:*:*:*:swift:*:*before 4.40.1VulnerableVapor Project
  • cpe:2.3:a:vapor_project:vapor:*:*:*:*:*:swift:*:* Versions before 4.40.1 Vulnerable ·Vapor Project

Remediation

  • Fix · GHSA-gcj9-jj38-hwmc github.com/vapor/vapor (SwiftURL) Fixed in 4.40.1 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-21328
  2. 2026-10-03 Alias added: GHSA-gcj9-jj38-hwmc

References

Patch 1

Advisory 3

Other 3

  • TI-2022-13064 DoS Vulnerability in URLEncodedFormDecoder in Vapor CVSS 3.1HIGH 7.5
  • TI-2022-13051 Integer Overflow in Vapor's HTTP Range Request CVSS 3.1HIGH 7.5
  • TI-2026-22762 LeafKit's HTML escaping may be skipped for Collection values, enabling XSS CVSS 4.0MEDIUM 6.9
  • TI-2026-21572 Leaf-kit html escaping does not work on characters that are part of extended grapheme cluster CVSS 3.1MEDIUM 6.1
  • TI-2021-12410 Untrusted data fed into `Data.init(base32Encoded:)` can result in exposing server memory and/or crash CVSS 3.1CRITICAL 9.1
  • TI-2020-12002 Arbitrary file read un Vapor CVSS 3.1HIGH 8.5
See all 10 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences