GHSA-c69g-56f8-xwqj: Netty: [codec-http2] Lack of Host Header Deduplication in HTTP/2→HTTP/1.x Translation Leads to Request Routing Bypass
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.
Details
Original advisory: https://github.com/advisories/GHSA-c69g-56f8-xwqj
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-599000.29% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 21% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-59900 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
More from GitHub Security Advisories
- mediumGHSA-jr6p-8pjj-mfx6: Capsule has an incomplete fix of CVE-2026-22872: TenantResource RawItems and Generators s…2026-07-31
- mediumGHSA-68cj-mvg9-rgm2: Capsule: CapsuleConfiguration NodeMetadata regex fields lack webhook validation, allowing…2026-07-31
- mediumGHSA-ff84-5f28-78qj: re2: Out-of-bounds heap read in `exec`/`test`/`match` via attacker-influenced `lastIndex`…2026-07-31
- mediumGHSA-6hxr-mr5r-9836: re2: Global `String.prototype.match` with an empty-matchable pattern never advances → inf…2026-07-31
- mediumGHSA-x83g-979r-f5fh: Sylius Mollie Plugin has unauthenticated IDOR that leaks order token and customer PII2026-07-31