Vulnerability in io.netty:netty-codec-http3 (CVE-2026-44892)
Summary
Vulnerability in io.netty:netty-codec-http3 (CVE-2026-44892). Risk of unauthorized operations or information disclosure. Exploitable via Http3ConnectionHandler. Mitigation: upgrade to 4.2.15.Final or later.
Original description
The description as published by the source.
Summary
The default configuration of the Http3ConnectionHandler in the Netty HTTP/3 codec lacks an enforced maximum header size limit. When a peer does not explicitly specify HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE, the implementation defaults to an unbounded limit. This insecure default configuration allows a malicious client or server to send an enormous number of headers, leading to a memory exhaustion Denial of Service via an OutOfMemoryError.
Details
Netty securely limits header sizes for older protocols. In HTTP/1.1, Netty strictly enforces an 8192-byte limit out-of-the-box via HttpObjectDecoder. For HTTP/2, while RFC 9113 specifies that SETTINGS_MAX_HEADER_LIST_SIZE defaults to unlimited, Netty securely overrides this RFC default by enforcing an 8192-byte limit (Http2CodecUtil.DEFAULT_HEADER_LIST_SIZE).
However, this secure-by-default configuration is missing in the HTTP/3 implementation. While Netty provides a mechanism to configure the maximum header field section size via Http3Settings, its out-of-the-box behaviour strictly follows RFC 9114's unlimited default.
Because many developers rely on the framework's default configurations and basic constructors, their applications are unknowingly left vulnerable. This nearly infinite default limit is passed into Http3FrameCodec#newFactory and stored as maxHeaderListSize inside Http3FrameCodec.
A bad actor can continuously send HTTP/3 headers within a connection, exploiting the insecure de…
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-2026-44892 has been found in io.netty:netty-codec-http3.
Attackers can target a specific entry point like Http3ConnectionHandler over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade io.netty:netty-codec-http3 to 4.2.15.Final or later.
If unsure, ask your IT team or search "io.netty:netty-codec-http3 CVE-2026-44892" on the vendor's site.
CVE-2026-44892 (io.netty:netty-codec-http3) — CWE-1188 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Http3ConnectionHandler / HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE / OutOfMemoryError / HttpObjectDecoder
Patched: 4.2.15.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.
A vulnerability (CWE-1188) exists in io.netty:netty-codec-http3. Attackers reach the vulnerable code path via Http3ConnectionHandler without authentication.
Check the vendor advisory for the affected versions of io.netty:netty-codec-http3. Attack surface: Http3ConnectionHandler / HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE / OutOfMemoryError / HttpObjectDecoder.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 4.2.15.Final.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
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
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1Identify 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-codec-http3 を使っているサービスとバージョンを洗い出す。
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2Apply patch patch
Upgrade io.netty:netty-codec-http3 to 4.2.15.Finalステージング環境で 4.2.15.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。
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3Post-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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-44892 netty
- Ubuntu UBUNTU-CVE-2026-44892 netty
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com