CVE-2026-55833
HIGHNetty SPDY zlib header block continues decoded expansion after maxHeaderSize truncation
Title source: cnaDescription
Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty SPDY header decoding continues inflating zlib-compressed header blocks after the raw header parser has exceeded `maxHeaderSize` and marked the frame truncated in `SpdyFrameCodec`, allowing a remote peer to send a small compressed `HEADERS` block that expands into much larger raw header data and causes compression-amplified CPU and allocation churn. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.
References (5)
Core 5
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/netty/netty/security/advisories/GHSA-mvh2-crg5-v77c
X_Refsource_Misc x_refsource_misc
https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b
X_Refsource_Misc x_refsource_misc
https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6
X_Refsource_Misc x_refsource_misc
https://github.com/netty/netty/releases/tag/netty-4.1.136.Final
X_Refsource_Misc x_refsource_misc
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final
Scores
CVSS v3
7.5
EPSS
0.0042
EPSS Percentile
34.9%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-400
Status
published
Products (5)
io.netty/netty-codec-http
4.1.0.Final - 4.1.136.FinalMaven
io.netty/netty-codec-http
4.2.0.Final - 4.2.16.FinalMaven
netty/netty
4.1.0 - 4.1.136
netty/netty
>= 4.1.0.Final, < 4.1.136.Final
netty/netty
>= 4.2.0.Final, < 4.2.16.Final
Published
Jul 21, 2026
Tracked Since
Jul 21, 2026