Vulnerability in github.com/vapor/vapor (CVE-2021-21328)
Summary
Vulnerability in github.com/vapor/vapor (CVE-2021-21328). Risk of unauthorized operations or information disclosure. Exploitable via DefaultResponder. Mitigation: upgrade to 4.40.1 or later.
Original description
The description as published by the source.
Impact
This is a DoS attack against anyone who Bootstraps a metrics backend for their Vapor app with the following attack vector:
- send unlimited requests against a vapor instance with different paths. this will create “unlimited” counters and timers, which will eventually drain the system.
- 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:
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2021-21328 has been found in github.com/vapor/vapor.
Attackers can target a specific entry point like DefaultResponder over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade github.com/vapor/vapor to 4.40.1 or later.
If unsure, ask your IT team or search "github.com/vapor/vapor CVE-2021-21328" on the vendor's site.
CVE-2021-21328 (github.com/vapor/vapor) — CWE-400
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: DefaultResponder / vapor_route_undefined
Patched: 4.40.1 — apply immediately
Workaround: Don't bootstrap a metrics system or upgrade to 4.40.1
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-400) exists in github.com/vapor/vapor. Attackers reach the vulnerable code path via DefaultResponder without authentication.
Check the vendor advisory for the affected versions of github.com/vapor/vapor. Attack surface: DefaultResponder / vapor_route_undefined.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 4.40.1.
Workaround: Don't bootstrap a metrics system or upgrade to 4.40.1
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/vapor/vapor' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'github.com/vapor/vapor' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/vapor/vaporを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
Don't bootstrap a metrics system or upgrade to 4.40.1パッチが適用されるまでの応急処置として、Don't bootstrap a metrics system or upgrade to 4.40.1 を実施。回避策の副作用 (機能低下) を確認した上で。
-
3Apply patch patch
Upgrade github.com/vapor/vapor to 4.40.1ステージング環境で 4.40.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
4Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- web github.com
- web github.com
- web github.com
- web github.com
- web vapor.codes