CVE-2026-59901

Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads to Event-Loop Thread Hang

State: Published
Severity: 8.7 High
Published: Jul 29, 2026
Updated: Jul 29, 2026
Reserved: Jul 7, 2026

Description

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the `Bzip2Decoder` handler in Netty's compression codec pipeline is vulnerable to a denial-of-service attack through a malformed bzip2 stream that permanently captures the event-loop thread in an infinite loop. The vulnerability exists in the run-length encoding (RLE) state machine within [`Bzip2BlockDecompressor.read()`]. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

Scores

CVSS	Score	Vector	Source
4.0	8.7 High	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N	GitHub_M

Weaknesses

CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')

Affected Products

Product	Versions
nettynetty	>=4.2.0.Final, < 4.2.16.FinalAffected < 4.1.136.FinalAffected

References

https://github.com/netty/netty/security/advisories/GHSA-558v-64gr-wgg4

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