CVE-2026-46340

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.

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

CVE-2026-46340 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.2.15.Final, 4.1.135.Final); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-46340? CVE-2026-46340 is a high-severity allocation of resources without limits or throttling vulnerability in io.netty:netty-transport-sctp (maven), affecting versions >= 4.2.0.Final, <= 4.2.14.Final. It is fixed in 4.2.15.Final, 4.1.135.Final. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. How severe is CVE-2026-46340? CVE-2026-46340 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of io.netty:netty-transport-sctp are affected by CVE-2026-46340? io.netty:netty-transport-sctp (maven) versions >= 4.2.0.Final, <= 4.2.14.Final is affected.
4. Is there a fix for CVE-2026-46340? Yes. CVE-2026-46340 is fixed in 4.2.15.Final, 4.1.135.Final. Upgrade to this version or later.
5. Is CVE-2026-46340 exploitable, and should I be worried? Whether CVE-2026-46340 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-46340 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-46340?
   • Upgrade io.netty:netty-transport-sctp to 4.2.15.Final or later
   • Upgrade io.netty:netty-transport-sctp to 4.1.135.Final or later