High severity · published Jul 29, 2026
CVE-2026-59901
Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads to Event-Loop Thread Hang
7.5
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 40% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NE
netty · netty
>=4.2.0.Final, < 4.2.16.Final; < 4.1.136.Final · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-59901
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-59901
Vendor Advisory
https://github.com/netty/netty/security/advisories/GHSA-558v-64gr-wgg4
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