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CVE-2025-9784 high CVSS 7.5

Vulnerability in io.undertow:undertow-core (CVE-2025-9784)

Summary

Vulnerability in io.undertow:undertow-core (CVE-2025-9784). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 2.3.20.Final or later.

Original description

The description as published by the source.

A flaw was found in Undertow where malformed client requests can trigger server-side stream resets without triggering abuse counters. This issue, referred to as the "MadeYouReset" attack, allows malicious clients to induce excessive server workload by repeatedly causing server-side stream aborts. While not a protocol bug, this highlights a common implementation weakness that can be exploited to cause a denial of service (DoS).

Source: NIST National Vulnerability Database NVD GitHub Advisory

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-2025-9784 has been found in io.undertow:undertow-core.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade io.undertow:undertow-core to 2.3.20.Final or later.
If unsure, ask your IT team or search "io.undertow:undertow-core CVE-2025-9784" on the vendor's site.

CVE-2025-9784 (io.undertow:undertow-core) — CWE-770 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 2.3.20.Final — apply immediately
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.

❓ What is the problem

A vulnerability (CWE-770) exists in io.undertow:undertow-core.

📍 Affected scope

Check the vendor advisory for the affected versions of io.undertow:undertow-core.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 2.3.20.Final.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで io.undertow:undertow-core を使っているサービスとバージョンを洗い出す。

  2. 2
    Apply patch patch 
    Upgrade io.undertow:undertow-core to 2.3.20.Final

    ステージング環境で 2.3.20.Final 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。

  3. 3
    Post-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

maven io.undertow:undertow-core
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.20.Final"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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