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NettyApplication

CVE-2026-44892

HIGH · 7.5 CVSS v3.1 Published 2026-06-12
Fix available
A fix is available. Upgrade to 4.2.15 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Netty is a network application framework for development of protocol servers and clients. Prior to version 4.2.15.Final, 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`. Version 4.2.15.Final contains a patch.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Netty's Http3ConnectionHandler in versions prior to 4.2.15.Final has an insecure default configuration that does not enforce a maximum header size limit. When HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE is not explicitly configured by either peer, the implementation defaults to an unbounded limit, allowing a malicious client or server to send excessive headers and cause memory exhaustion via OutOfMemoryError.

MitigationUpgrade to Netty 4.2.15.Final or explicitly configure HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE with an appropriate maximum header size limit in the Http3ConnectionHandler to prevent unbounded memory allocation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
NettyApplication
Affected:>= 4.2.0, < 4.2.15

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Netty version
    Inspect your project's dependency management file (Maven pom.xml, Gradle build.gradle, or similar) for the netty version. Also check any Netty JAR files present in your deployment for the version annotation.
    Affected if The Netty version is 4.2.0 through 4.2.14 (any version < 4.2.15)
  2. Confirm Http3ConnectionHandler is in use
    Search your codebase for imports or references to io.netty.incubator.codec.http3.Http3ConnectionHandler. Also check your server or client initialization code for HTTP/3 protocol setup.
    Affected if Your application uses Http3ConnectionHandler for HTTP/3 communication
  3. Check for explicit HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE configuration
    Search configuration files and application code for any setting of HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE or similar max header size configuration on the Http3ConnectionHandler or Http3Settings. Look for methods like setMaxFieldSectionSize or equivalent configuration APIs.
    Affected if HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE is NOT explicitly configured (the check finds no such setting)
  4. Verify runtime configuration state
    If possible, enable debug logging for Netty's HTTP/3 codec or inspect the Http3ConnectionHandler at runtime to verify the actual max field section size value being used.
    Affected if The runtime shows an unbounded or very large max field section size value with no explicit limit set

You are affected if your Netty version is less than 4.2.15 AND you use Http3ConnectionHandler without explicitly configuring a maximum header size limit, because the default unbounded limit can be exploited to exhaust memory.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.2.15 or later
Fixed in 4.2.15
Interim mitigation

Upgrade to Netty 4.2.15.Final or explicitly configure HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE with an appropriate maximum header size limit in the Http3ConnectionHandler to prevent unbounded memory allocation.

Recommended fix High confidence

4.2.15.Final

  1. Check the current Netty version in your project dependencies (e.g., pom.xml, build.gradle, or equivalent)
  2. Update the Netty dependency to version 4.2.15.Final or later. For Maven, update the pom.xml dependency version. For Gradle, update the version in build.gradle
  3. Rebuild the project to incorporate the new Netty version
  4. Redeploy the application with the updated Netty library
  5. Verify the application starts correctly and HTTP/3 functionality works as expected
Caveat This is a patch release focused on security; minimal breaking changes expected but review release notes for any HTTP/3 codec changes

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Netty Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-44892 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data