🛡️ CVE-2021-37136 — netty

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

Description

Bzip2Decoder doesn't allow setting size restrictions for decompressed data

Impact

The Bzip2 decompression decoder function doesn't allow setting size restrictions on the decompressed output data (which affects the allocation size used during decompression).

All users of Bzip2Decoder are affected. The malicious input can trigger an OOME and so a DoS attack

Workarounds

No workarounds other than not using the Bzip2Decoder

References

Relevant code areas:

https://github.com/netty/netty/blob/netty-4.1.67.Final/codec/src/main/java/io/netty/handler/codec/compression/Bzip2Decoder.java#L80

https://github.com/netty/netty/blob/netty-4.1.67.Final/codec/src/main/java/io/netty/handler/codec/compression/Bzip2Decoder.java#L294

https://github.com/netty/netty/blob/netty-4.1.67.Final/codec/src/main/java/io/netty/handler/codec/compression/Bzip2Decoder.java#L305

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-2021-37136 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-2021-37136 is recorded against 3 packages.

  • io.netty:netty
  • io.netty:netty-codec (fixed in 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-2021-37136 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 — 4.1.68.Final
org.jboss.netty:netty — —

References

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