GHSA-xhv5-w9c5-2r2w · 深刻度： high · エコシステム： maven — Unbounded connection acceptance in http4s-blaze-server
Http4s (http4s-blaze-server) is a minimal, idiomatic Scala interface for HTTP services. Http4s before versions 0.21.17, 0.22.0-M2, and 1.0.0-M14 have a vulnerability which can lead to a denial-of-service. Blaze-core, a library underlying http4s-blaze-server, accepts connections unboundedly on its selector pool. This has the net effect of amplifying degradation in services that are unable to handle their current request load, since incoming connections are still accepted and added to an unbounded queue. Each connection allocates a socket handle, which drains a scarce OS resource. This can also confound higher level circuit breakers which work based on detecting failed connections. http4s provides a general "MaxActiveRequests" middleware mechanism for limiting open connections, but it is enforced inside the Blaze accept loop, after the connection is accepted and the socket opened. Thus, the limit only prevents the number of connections which can be simultaneously processed, not the number of connections which can be held open. In 0.21.17, 0.22.0-M2, and 1.0.0-M14, a new "maxConnections" property, with a default value of 1024, has been added to the `BlazeServerBuilder`. Setting the value to a negative number restores unbounded behavior, but is strongly disrecommended. The NIO2 backend does not respect `maxConnections`. Its use is now deprecated in http4s-0.21, and the option is removed altogether starting in http4s-0.22. There are several possible workarounds described in the refrenced GitHub Advisory GHSA-xhv5-w9c5-2r2w.
総合評価: CVE-2021-21294 は中リスク（59.6/100）。CVSS 深刻度は高。悪用される可能性が高い（EPSS 2.15%、80 パーセンタイル） 根拠: 直近 1 日で EPSS が +1.74% 上昇。悪用への関心が高まっている可能性があります。 推奨対応: 影響資産を整理し、修補計画に組み込んでください。
リスクは変動します。再評価に基づき、本ページの表示内容を更新しています。
EPSS は日次で悪用されやすさの相対度合いを推定します。パーセンタイルは採点済み CVE の中での相対位置（高いほど相対的に深刻）を示します。
| # | 日付 | 旧 EPSS スコア | 新 EPSS スコア | Δ（新 − 旧） |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.41% | 2.15% | +1.74% |
| 2 | 2025-10-25 | 0.53% | 0.41% | -0.12% |
| 3 | 2025-04-29 | — | 0.53% | — |
EPSS の全履歴 （全 12 件）
この CVE の CVSS 指標。
| ベーススコア | バージョン | 深刻度 | ベクトル | 悪用しやすさ | 影響 | スコアの出典 |
|---|---|---|---|---|---|---|
| 7.5 | 3.1 | HIGH |
|
3.9 | 3.6 | [email protected] |
| 7.5 | 3.1 | HIGH |
|
3.9 | 3.6 | [email protected] |
| 5.0 | 2.0 | MEDIUM |
|
10.0 | 2.9 | [email protected] |
GHSA-xhv5-w9c5-2r2w · 深刻度： high · エコシステム： maven — Unbounded connection acceptance in http4s-blaze-server
| URL | タグ |
|---|---|
| https://github.com/http4s/blaze/security/advisories/GHSA-xmw9-q7x9-j5qc | Third Party Advisory |
| https://github.com/http4s/http4s/commit/987d6589ef79545b9bb2324ac4bdebf82d9a0171 | Patch Third Party Advisory |
| https://github.com/http4s/http4s/security/advisories/GHSA-xhv5-w9c5-2r2w | Third Party Advisory |