In short
- CVE-2026-46340 is a HIGH (CVSS 7.5) vulnerability affecting io.netty:netty-transport-sctp, netty (netty).
- Chance of exploitation in the next 30 days (EPSS): 0.61%, higher than 49.0% of all vulnerabilities.
- Fix: update to 4.2.15.Final, 4.1.135.Final, 4.2.15, 4.1.135 or later.
| Package | Affected versions | Patched versions |
|---|
| io.netty:netty-transport-sctp Maven | ≥ 4.2.0.Final, < 4.2.15.Final< 4.1.135.Final
| 4.2.15.Final4.1.135.Final
|
| netty | ≥ 4.2.0, < 4.2.15< 4.1.135
| 4.2.154.1.135
|
Description
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.
NVD description
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.
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