CVE-2026-59900Netty is an asynchronous, event-driven network application framework.
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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.
- CVSS
- 5.3 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- Weakness (CWE)
- CWE-444
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Analyzed
- Record last updated
- Aug 6, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
netty netty netty:netty | before 4.1.136; from 4.2.0 before 4.2.16 | NVD |
References
- https://github.com/netty/netty/releases/tag/netty-4.1.136.Finalrelease-notes
- https://github.com/netty/netty/releases/tag/netty-4.2.16.Finalrelease-notes
- https://github.com/netty/netty/security/advisories/GHSA-c69g-56f8-xwqjvendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.