CVE-2026-56819
Netty: HTTP/2 decompression leaks ByteBuf reference count when the decompressor channel is already closed (Direct memory leak / OOM DoS)
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, 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(...)` calls `decompressor.writeInbound(data.retain())` and does not release the retained buffer on the error path, eventually exhausting direct memory and crashing the JVM. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.
- Affected
- netty
- CVSS v3.1 GITHUB
- 7.5 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS
- 0.66% chance of exploitation in the next 30 days, 51st percentile
- Published
- 2026-07-21
- Updated
- 2026-07-23
Proof-of-concept exploits (1)
Security advisories
- netty/netty/security/advisories/GHSA-93wv-jw9v-4972
- netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b