CVE-2026-46340 — Netty: SCTP reassembly nests buffers without bound

Description (CNA)

Netty 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.

Affected (CNA)

Vendor / product	Versions
netty / netty	affected >= 4.2.0.Final, < 4.2.15.Final; affected < 4.1.135.Final

CWE

CWE-770

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

A flaw was found in netty-transport-sctp. A remote attacker can exploit this vulnerability by sending specially crafted, non-complete Stream Control Transmission Protocol (SCTP) message fragments. This can lead to unbounded memory growth within the application, causing a Denial of Service (DoS) condition. The affected component fails to limit the size or number of these fragments, allowing an attacker to consume excessive system resources.