CVE-2026-46340
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 · uneditedNetty is a network application framework for development of protocol servers and clients. In versions of netty-transport-sctp prior to 4.1.135.Final and 4.2.15.Final, for each non-complete SctpMessage fragment the handler does `fragments.put(streamId, Unpooled.wrappedBuffer(frag, byteBuf))`, wrapping the previous accumulator and the new slice into a *new* CompositeByteBuf every time. After N fragments the accumulator is an N-deep chain of composites, each holding references and component arrays; readableBytes()/getBytes() on the final buffer recurse N levels. There is no limit on N, on total bytes, or on the number of streamIdentifiers an attacker can open (each gets its own map entry). A peer that never sets the `complete` flag can grow this structure indefinitely from tiny 1-byte DATA chunks. Versions 4.1.135.Final and 4.2.15.Final patch the issue.
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 confidenceThis is a resource exhaustion vulnerability in Netty's SCTP transport handler. For each non-complete SCTP message fragment, the handler creates a new CompositeByteBuf wrapping the previous accumulator and new slice, resulting in an N-deep chain of composites after N fragments. An attacker can send unlimited 1-byte DATA chunks without setting the complete flag, causing unbounded memory growth and DoS.
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< 4.1.135>= 4.2.0, < 4.2.15CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify if Netty SCTP dependency is presentSearch your project's dependency tree (Maven pom.xml, Gradle build.gradle, or classpath) for netty-sctp, netty-transport-sctp, or io.netty.transport.sctp packagesAffected if Any netty-sctp or netty-transport-sctp dependency is found in the runtime classpath
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Determine the installed Netty SCTP versionLocate the netty-transport-sctp JAR file or dependency declaration and note its version number (for example, 4.1.108.Final or 4.2.10.Final)Affected if The version is lower than 4.1.135.Final or falls between 4.2.0.Final and 4.2.14.Final inclusive
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Verify if SCTP channels are in useSearch codebase for imports or usage of io.netty.channel.sctp.SctpChannel, io.netty.channel.sctp.SctpServerChannel, or SctpChannelConfigurationAffected if SCTP channel classes are instantiated or configured in the application code
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Confirm SCTP is exposed to untrusted network trafficReview server configuration for SctpChannel.bind() or SctpServerChannel.bind() calls that bind to accessible network interfaces (0.0.0.0 or non-loopback addresses)Affected if SCTP channels are bound to reachable network addresses and can receive external SCTP traffic
A user is affected if they run any Netty SCTP version below 4.1.135 or between 4.2.0 and 4.2.14 with SCTP channels exposed to network traffic.
Generated from the published advisory. Verify against your own configuration.
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 · scoped4.1.1354.2.15
Upgrade to Netty version 4.1.135.Final or 4.2.15.Final or later which contains the patch. If immediate upgrade is not feasible, consider disabling SCTP transport or implementing upstream rate limiting on SCTP connections.
4.1.135.Final (for 4.1.x users) or 4.2.15.Final (for 4.2.x users)
- 1. Identify the current Netty version in use by checking project dependencies (Maven pom.xml, Gradle build.gradle, or equivalent)
- 2. Determine which major version line is in use (4.1.x or 4.2.x)
- 3. For projects using Netty 4.1.x: upgrade netty-transport-sctp (and preferably the entire netty BOM) to version 4.1.135.Final or later
- 4. For projects using Netty 4.2.x: upgrade netty-transport-sctp (and preferably the entire netty BOM) to version 4.2.15.Final or later
- 5. Rebuild and redeploy the application
- 6. Monitor for any regressions during testing, particularly around SCTP message handling
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-46340 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-46340 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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