CVE-2026-46340

Vulnerability 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.

CVSS Score

Affected Products

Related Weaknesses (CWE)

References

• https://github.com/netty/netty/releases/tag/netty-4.1.135.FinalRelease Notes
• https://github.com/netty/netty/releases/tag/netty-4.2.15.FinalRelease Notes
• https://github.com/netty/netty/security/advisories/GHSA-5xrh-qmmq-w6chVendor Advisory
• https://access.redhat.com/errata/RHSA-2026:37390
• https://access.redhat.com/errata/RHSA-2026:41951
• https://access.redhat.com/errata/RHSA-2026:50085
• https://access.redhat.com/errata/RHSA-2026:53644
• https://access.redhat.com/errata/RHSA-2026:53806
• https://access.redhat.com/security/cve/CVE-2026-46340
• https://bugzilla.redhat.com/show_bug.cgi?id=2488388
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46340.json