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Netty SpdyHttpDecoder: ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion

netty · CVE-2026-56745
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What is it?

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.

Evidence

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Exploitation

  • Public proof of concept
  • Exploited in the wild
  • Listed as known exploited
CVSS
8.7
EPSS
0.6%
First seen
7 d ago
Status
corroborated

All netty vulnerabilities