Netty: Memory Exhaustion in SctpMessageCompletionHandler
Summary
SctpMessageCompletionHandler does not limit the total size of buffered fragments, allowing an unauthenticated attacker to cause an OutOfMemoryError by sending large SCTP fragments.
Details
io.netty.handler.codec.sctp.SctpMessageCompletionHandler buffers fragments for incomplete SCTP messages. The fix for CVE-2026-46340 fixed unbounded memory growth by introducing limits on the number of concurrent incomplete messages (maxIncompleteSctpMessages) and the number of fragments per message (maxFragments).
While the count of fragments is now bounded, the handler still does not enforce a maximum size in bytes.
With the default limits of 128 messages and 128 fragments, and a typical max SCTP chunk size of 64KB, an attacker can consume up to ~1GB per connection. By opening a small number of concurrent connections, an attacker can easily exhaust the server's memory, causing an OutOfMemoryError.
Impact
Memory Exhaustion. Any application using Netty's SCTP transport with SctpMessageCompletionHandler is impacted.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | io.netty:netty-transport-sctp | >= 4.2.0.Final, < 4.2.17.Final, < 4.1.137.Final | 4.2.17.Final, 4.1.137.Final |
References
- https://github.com/netty/netty/security/advisories/GHSA-2qj4-mmr9-4v2f
- https://github.com/netty/netty/pull/17213
- https://github.com/netty/netty/pull/17217
- https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7
- https://github.com/netty/netty
- https://github.com/netty/netty/releases/tag/netty-4.1.137.Final
- https://github.com/netty/netty/releases/tag/netty-4.2.17.Final
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-400- Platform
- Java / Kotlin (Maven)
- Package
io.netty:netty-transport-sctp- Disclosed
- 17.08.2026
- Updated
- 11.10.2026 13:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-2qj4-mmr9-4v2f - CC BY 4.0
Vulnerability history: io.netty:netty-transport-sctp
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 06.2026 08.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 2
Disclosures per year
- 2026: 2
-
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