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Medium

netty-codec-http2: ByteBuf Reference-Count Leak in DelegatingDecompressorFrameListener Leads to Memory Exhaustion

  • Disclosed: 11.06.2026
  • Updated: 11.10.2026 13:20

Impact

The DelegatingDecompressorFrameListener class orchestrates HTTP/2 decompression by embedding a per-stream EmbeddedChannel that runs the appropriate decompression codec (gzip, deflate, zstd) and forwards decompressed chunks to a wrapped listener. Each decompressed chunk is a pooled ByteBuf handed to an anonymous ChannelInboundHandlerAdapter tail handler, which becomes the sole owner responsible for releasing it.

A remote peer could send frames that would result in the flow-controller throwing and so trigger a resource leak which at the end might take down the whole JVM due OOME.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Java / Kotlin (Maven) io.netty:netty-codec-http2 < 4.1.135.Final, >= 4.2.0.Alpha1, < 4.2.15.Final 4.1.135.Final, 4.2.15.Final

References

CVSS score 5.3/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness (CWE)
CWE-400, CWE-401, CWE-772
Platform
Java / Kotlin (Maven)
Package
io.netty:netty-codec-http2
Disclosed
11.06.2026
Updated
11.10.2026 13:20

Sources and licenses

OSV / GitHub Advisory Database - GHSA-c2gf-v879-257j - CC BY 4.0

Vulnerability history: io.netty:netty-codec-http2

All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (11) in the archive
Total entries
11
First → latest
03.2021 07.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • High 5
  • Medium 6

Disclosures per year

Severity:
  1. Netty: HTTP/2 decompression leaks ByteBuf reference count when the decompressor channel is already closed (Direct memory leak / OOM DoS)
    High · 7.5 CVE-2026-56819 >= 4.2.0, < 4.2.16.Final, >= 4.1.0.Final, < 4.1.136.Final 4.2.16.Final, 4.1.136.Final
  2. netty-codec-http2: ByteBuf Reference-Count Leak in DelegatingDecompressorFrameListener Leads to Memory Exhaustion this entry
    Medium · 5.3 CVE-2026-48043 < 4.1.135.Final, >= 4.2.0.Alpha1, < 4.2.15.Final 4.1.135.Final, 4.2.15.Final
  3. Netty: HttpContentDecompressor maxAllocation bypass when Content-Encoding set to br/zstd/snappy leads to decompression bomb DoS
    High · 7.5 CVE-2026-42587 >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Final 4.2.13.Final, 4.1.133.Final
  4. Netty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass
    High CVE-2026-33871 < 4.1.132.Final, >= 4.2.0.Alpha1, < 4.2.11.Final 4.1.132.Final, 4.2.11.Final
  5. Netty affected by MadeYouReset HTTP/2 DDoS vulnerability
    High · 7.5 CVE-2025-55163 >= 4.2.0.Alpha1, < 4.2.4.Final, < 4.1.124.Final 4.2.4.Final, 4.1.124.Final
  6. io.netty:netty-codec-http2 vulnerable to HTTP/2 Rapid Reset Attack
    High · 7.5 ghsa-xpw8-rcwv-8f8p < 4.1.100.Final 4.1.100.Final

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