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Vulnerability · Published Jun 12, 2026 · Assigned by GitHub_M

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

High 7.5

In plain English

A high-severity resource allocation without limits in netty from netty. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.6%top 50.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12nettyno fix listedDEBIAN-CVE-2026-46340
Debian:13nettyno fix listedDEBIAN-CVE-2026-46340
Debian:14nettyno fix listedDEBIAN-CVE-2026-46340
Mavenio.netty:netty-transport-sctp4.1.135.FinalGHSA-5xrh-qmmq-w6ch
Mavenio.netty:netty-transport-sctp4.2.15.FinalGHSA-5xrh-qmmq-w6ch
Ubuntu:25.10nettyno fix listedUBUNTU-CVE-2026-46340
Ubuntu:26.10nettyno fix listedUBUNTU-CVE-2026-46340

Affected products (as reported)

VendorProductVersions
netty netty >= 4.2.0.Final, < 4.2.15.Final< 4.1.135.Final

Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References