CVE-2026-55833: Netty SPDY zlib header block continues decoded expansion after maxHeaderSize truncation
Description
Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty SPDY header decoding continues inflating zlib-compressed header blocks after the raw header parser has exceeded `maxHeaderSize` and marked the frame truncated in `SpdyFrameCodec`, allowing a remote peer to send a small compressed `HEADERS` block that expands into much larger raw header data and causes compression-amplified CPU and allocation churn. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H · CWE-400
Tracked companies
Mapped from the CVE’s affected-product data, NVD CPE matches, vendor advisories or package feeds. A mapping means the vendor’s software is named, not that its hosted service was exposed.
Status incidents that name it
No tracked status incident names this CVE.
Affected vendors and products
netty: netty
References
- CVE record on cve.org (opens in new tab)
- NVD entry (opens in new tab)
- github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b (opens in new tab)
- github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6 (opens in new tab)
- github.com/netty/netty/releases/tag/netty-4.1.136.Final (opens in new tab)
- github.com/netty/netty/releases/tag/netty-4.2.16.Final (opens in new tab)
- github.com/netty/netty/security/advisories/GHSA-mvh2-crg5-v77c (opens in new tab)
- CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (opens in new tab)
- This product uses data from the NVD API but is not endorsed or certified by the NVD. (opens in new tab)
- Known Exploited Vulnerabilities catalog from CISA. (opens in new tab)
- EPSS scores from FIRST (Exploit Prediction Scoring System). (opens in new tab)