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Vapor's Metrics integration could cause a system drain

Moderate severity GitHub Reviewed Published Feb 22, 2021 in vapor/vapor • Updated Jun 19, 2023

Package

swift github.com/vapor/vapor (Swift)

Affected versions

<= 4.40.0

Patched versions

4.40.1

Description

Impact

This is a DoS attack against anyone who Bootstraps a metrics backend for their Vapor app with the following 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

Patches

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.

Workarounds

Don't bootstrap a metrics system or upgrade to 4.40.1

For more information

If you have any questions or comments about this advisory:

References

@0xTim 0xTim published to vapor/vapor Feb 22, 2021
Published by the National Vulnerability Database Feb 26, 2021
Published to the GitHub Advisory Database Jun 9, 2023
Reviewed Jun 9, 2023
Last updated Jun 19, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

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

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(63rd percentile)

Weaknesses

Uncontrolled Resource Consumption

The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Learn more on MITRE.

CVE ID

CVE-2021-21328

GHSA ID

GHSA-gcj9-jj38-hwmc

Source code

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