Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
CVE-2026-42587
Netty: HttpContentDecompressor maxAllocation bypass via Content-Encoding: br/zstd/snappy enables decompression bomb DoS
AV AC PR UI S C I A CVSS EPSS %ile KEV
N L N N U N N H 7.5 .0105 63.0 —
AFFECTED
Product Versions Fixed
netty >= 4.2.0.Alpha1, < 4.2.13.Final – —
netty-codec-http >= 4.2.0.Alpha1, < 4.2.13.Final – —
netty-codec-http2 >= 4.2.0.Alpha1, < 4.2.13.Final – —
TIMELINE
Apr 28 Reserved by GitHub_M
May 13 Published (CNA: GitHub_M)
Aug 13 EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added.
Sep 3 EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added.
Sep 7 EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added.
Sep 9 EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added.
Sep 11 EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added.
Sep 17 EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added.
Sep 18 EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added.
Description
Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpContentDecompressor accepts a maxAllocation parameter to limit decompression buffer size and prevent decompression bomb attacks. This limit is correctly enforced for gzip and deflate encodings via ZlibDecoder, but is silently ignored when the content encoding is br (Brotli), zstd, or snappy. An attacker can bypass the configured decompression limit by sending a compressed payload with Content-Encoding: br instead of Content-Encoding: gzip, causing unbounded memory allocation and out-of-memory denial of service. The same vulnerability exists in DelegatingDecompressorFrameListener for HTTP/2 connections. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.
Lifecycle
Complete event history — 9 events, chronological
| Date | Event | Detail |
|---|
| April 28, 2026 | Reserved | Reserved by GitHub_M |
| May 13, 2026 | Published | Published (CNA: GitHub_M) |
| August 13, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added. |
| September 3, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added. |
| September 7, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added. |
| September 9, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added. |
| September 11, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added. |
| September 17, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added. |
| September 18, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-42587 (netty). Public exploit reference added. |
Affected
Affected products and packages — 3 rows
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| netty | netty | — | >= 4.2.0.Alpha1, < 4.2.13.Final | — |
| io.netty | netty-codec-http | — | >= 4.2.0.Alpha1, < 4.2.13.Final | — |
| io.netty | netty-codec-http2 | — | >= 4.2.0.Alpha1, < 4.2.13.Final | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-42587 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.
