CVE-2026-55833
High
Description
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.
SeverityHigh
CVSS7.5
Exploit probability—
ProductNetty
PublishedJul 21, 2026
First seenJul 21, 2026
Weakness typeCWE-400Uncontrolled resource consumption
How to fix
Update
- netty netty4.1.136, 4.2.16 or later
- io.netty:netty-codec-http4.2.16.Final, 4.1.136.Final or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| netty netty | 4.1.0 ≤ v < 4.1.136, 4.2.0 ≤ v < 4.2.16 | 4.1.136, 4.2.16 |
| io.netty:netty-codec-httpMaven | 4.2.0.Final ≤ v < 4.2.16.Final, 4.1.0.Final ≤ v < 4.1.136.Final | 4.2.16.Final, 4.1.136.Final |
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