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CVE-2026-44249 high CVSS 8.1

Vulnerability in io.netty:netty-handler (CVE-2026-44249)

Summary

Vulnerability in io.netty:netty-handler (CVE-2026-44249). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 4.1.135.Final or later.

Original description

The description as published by the source.

Netty is a network application framework for development of protocol servers and clients. In netty-handler prior to versions 4.1.135.Final and 4.2.15.Final, an attacker can bypass IPv6 subnet rules due to an incorrect masking operation in IpSubnetFilterRule.compareTo(). Valid public IP addresses can bypass the restrictions. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

Source: GitHub Security Advisories (Global) 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-2026-44249 has been found in io.netty:netty-handler.
Successful exploitation can lead to full system takeover. CVSS score: 8.1/10.
What to do: upgrade io.netty:netty-handler to 4.1.135.Final or later.
If unsure, ask your IT team or search "io.netty:netty-handler CVE-2026-44249" on the vendor's site.

CVE-2026-44249 (io.netty:netty-handler) — CWE-284 / CVSS v3 8.1
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 4.1.135.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-284) exists in io.netty:netty-handler.

📍 Affected scope

Check the vendor advisory for the affected versions of io.netty:netty-handler.

🔥 Severity

Severity: High (CVSS 8.1/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 4.1.135.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.netty:netty-handler 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.netty:netty-handler to 4.1.135.Final

    ステージング環境で 4.1.135.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.netty:netty-handler
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.1.135.Final"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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