Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Netty's netty-codec-http package, versions 4.2.0.Final up to but not including 4.2.16.Final and 4.1.0.Final up to but not including 4.1.136.Final, is vulnerable. A remote peer that can speak SPDY to a pipeline using SpdyFrameCodec can send a small compressed HEADERS block that keeps inflating after the header size limit is exceeded, causing denial of service through excess CPU and memory use. Upgrade to 4.2.16.Final or 4.1.136.Final. The source gives few details on workarounds.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 7.5 | High | 3.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0066, the 52nd percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 14 Jul 2026, 19:56 UTC Published by the maintainers as a GitHub repository advisory
- 31 Oct 2026, 14:17 UTC First seen by agentprime
- 31 Oct 2026, 14:17 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-mvh2-crg5-v77c
- OSV: GHSA-mvh2-crg5-v77c
- github.com/netty/netty/security/advisories/GHSA-mvh2-crg5-v77c
- nvd.nist.gov/vuln/detail/CVE-2026-55833
- github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b
- github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6
- github.com/netty/netty
- github.com/netty/netty/releases/tag/netty-4.1.136.Final
- github.com/netty/netty/releases/tag/netty-4.2.16.Final