CVE-2021-21328
mediumpriority · track · 22EPSS 0.018 · 79 %ileEUUSEPSS · scored 2026-10-28
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode
weaknesses
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affected products (3)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- GHSA-gcj9-jj38-hwmcVapor's Metrics integration could cause a system drain2023-06-09ghsa · osvUS
### 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: * Open an issue in [Vapor](https://github.com/vapor/vapor) * Ask in [Discord](http://vapor.team)
also known as (3)
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sources
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references (13)
External citations — patches, advisories, analysis.
- https://github.com/vapor/vapor/commit/e3aa712508db2854ac0ab905696c65fd88fa7e23cnnvd
- https://github.com/vapor/vapor/releases/tag/4.40.1cnnvd
- https://github.com/vapor/vapor/security/advisories/GHSA-gcj9-jj38-hwmccnnvd
- https://nvd.nist.gov/vuln/detail/CVE-2021-21328cnnvd
- https://vapor.codes/cnnvd
- https://github.com/vapor/vapor/commit/e3aa712508db2854ac0ab905696c65fd88fa7e23enisa_euvd
- https://github.com/vapor/vapor/releases/tag/4.40.1enisa_euvd
- https://github.com/vapor/vapor/security/advisories/GHSA-gcj9-jj38-hwmcenisa_euvd
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