🛡️ CVE-2021-37137 — netty

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-400 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

SnappyFrameDecoder doesn't restrict chunk length any may buffer skippable chunks in an unnecessary way

Impact

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.

Impact

All users of SnappyFrameDecoder are affected and so the application may be in risk for a DoS attach due excessive memory usage.

References

https://github.com/netty/netty/blob/netty-4.1.67.Final/codec/src/main/java/io/netty/handler/codec/compression/SnappyFrameDecoder.java#L79

https://github.com/netty/netty/blob/netty-4.1.67.Final/codec/src/main/java/io/netty/handler/codec/compression/SnappyFrameDecoder.java#L171

https://github.com/netty/netty/blob/netty-4.1.67.Final/codec/src/main/java/io/netty/handler/codec/compression/SnappyFrameDecoder.java#L185

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Weakness class

CVE-2021-37137 is classified as CWE-400: Uncontrolled Resource Consumption. A request can consume memory, CPU or storage without limit, exhausting capacity for everyone else.

Affected software

CVE-2021-37137 is recorded against 3 packages.

  • io.netty:netty
  • io.netty:netty-codec (from 4.0.0 up to 4.1.68.Final)
  • org.jboss.netty:netty

Timeline and source

Published on 9 September 2021 and last revised on 8 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
www.oracle.com (Web)
www.oracle.com (Web)
www.oracle.com (Web)
www.debian.org (Web)
security.netapp.com (Web)
lists.debian.org (Web)
lists.apache.org (Web)
lists.apache.org (Web)
lists.apache.org (Web)
lists.apache.org (Web)
lists.apache.org (Web)
lists.apache.org (Web)

CVE-2021-37137 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE CWE-400
Public Exploit ✅ No
Source OSV
Published 2021-09-09
Updated 2026-08-12
Modified 2026-07-08
Fix URL N/A

Affected Packages

Software From version Fixed in
io.netty:netty — —
io.netty:netty-codec 4.0.0 4.1.68.Final
org.jboss.netty:netty — —

References

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