CVE-2026-56745 Details
Description
Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and 4.1.0.Final through 4.1.135.Final, the `SpdyHttpDecoder` handler in Netty's SPDY-to-HTTP codec allocates a pooled `ByteBuf` when processing a client-initiated `SYN_STREAM` frame with `FLAG_FIN=0` and stores the partially constructed `FullHttpRequest` in `messageMap`; when the remote peer sends `RST_STREAM` for that stream or the accumulated content exceeds `maxContentLength`, the decoder removes the entry but does not release the pooled `ByteBuf`, causing native memory exhaustion. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.
A memory leak vulnerability has been identified in Netty's SPDY-to-HTTP codec, specifically in versions 4.2.0.Final through 4.2.15.Final and 4.1.0.Final through 4.1.135.Final. The issue arises in the 'SpdyHttpDecoder' handler, which allocates a pooled 'ByteBuf' when processing client-initiated 'SYN_STREAM' frames with 'FLAG_FIN=0'. The decoder stores the partially constructed 'FullHttpRequest' in an internal map to accumulate subsequent 'DATA' frames. However, when the remote peer sends an 'RST_STREAM' for that stream or the accumulated content exceeds 'maxContentLength', the decoder removes the entry from the map but fails to release the pooled 'ByteBuf'. This oversight leads to native memory exhaustion.
Users can upgrade to Netty versions 4.2.16.Final or 4.1.136.Final, both of which include the necessary fix. Instructions for downloading these versions are available on the Netty GitHub Releases page.
Metrics
CVSS 4.0 Severity and Vector Strings:
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 22, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-400 | Uncontrolled Resource Consumption | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| netty netty | >= 4.1.0, < 4.1.136 >= 4.2.0, < 4.2.16 |
CPE
Remediation
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Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 30, 2026 | Initial Analysis | [email protected] |
| Jul 22, 2026 | CVE Modified | CISA-ADP |
| Jul 21, 2026 | New CVE Received | [email protected] |