CVSS 4.0
6.9 mediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:NCVE-2026-59900
Medium (6.9) in netty netty. EPSS 0.4% chance of exploitation in the next 30 days. Fixed in io.netty:netty-codec-http2 4.1.136.Final, 4.2.16.Final.
Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, Netty's HTTP/2-to-HTTP/1.x translation layer (`Http2StreamFrameToHttpObjectCodec` and `InboundHttp2ToHttpAdapter`) fails to deduplicate or validate `Host` headers when an HTTP/2 client supplies both the `:authority` pseudo-header and a literal `host` header in a single HEADERS frame. The translator maps `:authority` to `Host` and separately copies the literal `host` header, producing an `HttpRequest` object containing two `Host` headers with attacker-controlled differing values. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.
Severity
CVSS 3.1
5.3 mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N- EPSS
- 0.4% chance of exploitation in the next 30 days; higher than 34% of CVEs (scores of 2026-10-31)
- CWE
- CWE-444
- Published
- Modified
- Record from
- the NVD, synced
Affected
- netty:netty
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-c69g-56f8-xwqj | Maven | io.netty:netty-codec-http2 | >=4.2.0.Final <4.2.16.Final | 4.2.16.Final |
| GHSA-c69g-56f8-xwqj | Maven | io.netty:netty-codec-http2 | <4.1.136.Final | 4.1.136.Final |