CVE-2021-21328 Denial of Service

2021-02-2601:45:23

CWE-400

GitHub_M

www.cve.org

vapor

dos attack

swift

metrics backend

patched

defaultresponder

unlimited counters

CVSS3

5.3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

LOW

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

EPSS

0.002

Percentile

51.9%

JSON

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.

CNA Affected

[
  {
    "product": "vapor",
    "vendor": "vapor",
    "versions": [
      {
        "status": "affected",
        "version": "<= 4.40.0"
      }
    ]
  }
]