HIGH 7.5 GitHub
CVE-2026-56819
Netty: HTTP/2 decompression leaks ByteBuf reference count when the decompressor channel is already closed (Direct memory leak / OOM DoS)
### Summary
A remote, unauthenticated peer can leak one direct `ByteBuf` per HTTP/2 `DATA` frame in
applications that enable HTTP/2 content decompression via `DelegatingDecompressorFrameListener`.
When a `DATA` frame is processed for a stream whose decompressor has already been closed,
`Http2Decompressor.decompress(...)` retains the frame buffer but never releases it on the error
path, so its reference count never returns to zero. Repeating this over a long-lived HTTP/2
connection exhausts dire
Affected Products
- maven/io.netty:netty-codec-http2 >= 4.2.0, <= 4.2.15.Final
- maven/io.netty:netty-codec-http2 >= 4.1.0.Final, <= 4.1.135.Final
References
- https://github.com/advisories/GHSA-93wv-jw9v-4972
- https://github.com/netty/netty/security/advisories/GHSA-93wv-jw9v-4972
- https://nvd.nist.gov/vuln/detail/CVE-2026-56819
- https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b
This high severity vulnerability with a CVSS score of 7.5 was published on 2026-07-31 via GitHub. Affected: maven/io.netty:netty-codec-http2 >= 4.2.0, <= 4.2.15.Final, maven/io.netty:netty-codec-http2 >= 4.1.0.Final, <= 4.1.135.Final.
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