VULNERABILITY INTELLIGENCE
CVE-2021-21328
CVSS score5.3 MEDIUM
EPSS probability1.84%
CISA KEVNot currently listed
Published2021-02-26
Last modified2026-06-17
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Description
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.
Weakness classification
- CWE-400: Uncontrolled Resource Consumption
Primary references
- security-advisories@github.com — Patch, Third Party Advisory
- security-advisories@github.com — Release Notes, Third Party Advisory
- security-advisories@github.com — Third Party Advisory
- security-advisories@github.com — Product
- af854a3a-2127-422b-91ae-364da2661108 — Patch, Third Party Advisory
- af854a3a-2127-422b-91ae-364da2661108 — Release Notes, Third Party Advisory
- af854a3a-2127-422b-91ae-364da2661108 — Third Party Advisory
- af854a3a-2127-422b-91ae-364da2661108 — Product