CVE-2026-56866 HTTP/1 client connection desynchronization after CONNECT rejection in net/http
10
[
{
"vendor": "Go standard library",
"product": "net/http",
"collectionURL": "https://pkg.go.dev",
"packageName": "net/http",
"versions": [
{
"version": "0",
"lessThan": "1.26.9",
"status": "affected",
"versionType": "semver"
},
{
"version": "1.27.0-0",
"lessThan": "1.27.2",
"status": "affected",
"versionType": "semver"
}
],
"programRoutines": [
{
"name": "persistConn.readLoop"
},
{
"name": "Client.CloseIdleConnections"
},
{
"name": "Client.Do"
},
{
"name": "Client.Get"
},
{
"name": "Client.Head"
},
{
"name": "Client.Post"
},
{
"name": "Client.PostForm"
},
{
"name": "ClientConn.Close"
},
{
"name": "ClientConn.RoundTrip"
},
{
"name": "Get"
},
{
"name": "Head"
},
{
"name": "Post"
},
{
"name": "PostForm"
},
{
"name": "Transport.CloseIdleConnections"
},
{
"name": "Transport.NewClientConn"
},
{
"name": "Transport.RoundTrip"
},
{
"name": "http1ClientConn.Close"
},
{
"name": "http1ClientConn.RoundTrip"
}
],
"defaultStatus": "unaffected"
},
{
"vendor": "Go standard library",
"product": "net/http/httputil",
"collectionURL": "https://pkg.go.dev",
"packageName": "net/http/httputil",
"versions": [
{
"version": "0",
"lessThan": "1.26.9",
"status": "affected",
"versionType": "semver"
},
{
"version": "1.27.0-0",
"lessThan": "1.27.2",
"status": "affected",
"versionType": "semver"
}
],
"programRoutines": [
{
"name": "ReverseProxy.ServeHTTP"
},
{
"name": "DumpRequestOut"
}
],
"defaultStatus": "unaffected"
}
]Data
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08 Oct 2026 22:53Current
CVSS 3.17.5
EPSS0.00473
SSVC