CVE-2026-94439
Status: Awaiting AnalysisHigh (7.5)—
When an HTTP server handler sends a 2xx response to an HTTP/1 CONNECT request and returns without hijacking the connection, the server improperly continues to read and serve requests from the connection. Since a 2xx response to an HTTP/1 CONNECT converts the connection into a tunnel, the server should not treat the connection as continuing to contain HTTP. The impact of this misbehavior is mostly limited to potential request smuggling, where an intermediate proxy considers the data on the connection to be tunneled and the server considers it to be HTTP.
CVSS
- Version: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Base score: 7.5
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days: 0.32%
- Percentile among all scored CVEs: 23
- Score date: 10/14/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
🎯 ATT&CK techniques
How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.
- Exploitation
T1190Exploit Public-Facing Applicationinitial access85 % - Primary impact
T1557Adversary-in-the-Middlecredential access · collection75 % - Secondary impact
T1090Proxycommand and control70 %
Vulnerabilidad de servidor HTTP accesible remotamente sin autenticación (AV:N/PR:N) que permite request smuggling mediante respuesta CONNECT malformada. El smuggling de HTTP facilita suplantación (MITM) e inyección de proxies.
Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.
🛡️ ATT&CK mitigations that cover these techniques
CWEs
- CWE-444
References
Raw JSON (NVD)
Show
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"name": "ParseSetCookie"
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"name": "ParseTime"
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"name": "ReadRequest"
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"name": "ReadResponse"
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"name": "Redirect"
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{
"name": "Request.AddCookie"
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{
"name": "Request.BasicAuth"
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{
"name": "Request.Cookie"
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{
"name": "Request.Cookies"
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{
"name": "Request.CookiesNamed"
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{
"name": "Request.FormFile"
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{
"name": "Request.FormValue"
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{
"name": "Request.MultipartReader"
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{
"name": "Request.ParseForm"
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{
"name": "Request.ParseMultipartForm"
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{
"name": "Request.PostFormValue"
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{
"name": "Request.Referer"
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{
"name": "Request.SetBasicAuth"
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{
"name": "Request.UserAgent"
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{
"name": "Request.Write"
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{
"name": "Request.WriteProxy"
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{
"name": "Response.Cookies"
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{
"name": "Response.Location"
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{
"name": "Response.Write"
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{
"name": "ResponseController.EnableFullDuplex"
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"name": "ResponseController.Flush"
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{
"name": "Serve"
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{
"name": "ServeContent"
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"name": "ServeFile"
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"name": "ServeFileFS"
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"name": "ServeTLS"
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"name": "Server.ListenAndServeTLS"
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{
"name": "Server.Serve"
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"name": "Server.ServeTLS"
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{
"name": "Server.SetKeepAlivesEnabled"
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{
"name": "Server.Shutdown"
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{
"name": "SetCookie"
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"name": "Transport.CancelRequest"
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"name": "Transport.Clone"
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"name": "bodyLocked.Read"
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"name": "cancelTimerBody.Close"
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"published": "2026-10-08T23:17:04.760",
"references": [
{
"url": "https://go.dev/cl/847311",
"source": "security@golang.org"
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{
"url": "https://go.dev/issue/81744",
"source": "security@golang.org"
},
{
"url": "https://groups.google.com/g/golang-announce/c/U2fTuyDJznI",
"source": "security@golang.org"
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{
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"source": "security@golang.org"
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"value": "When an HTTP server handler sends a 2xx response to an HTTP/1 CONNECT request and returns without hijacking the connection, the server improperly continues to read and serve requests from the connection. Since a 2xx response to an HTTP/1 CONNECT converts the connection into a tunnel, the server should not treat the connection as continuing to contain HTTP. The impact of this misbehavior is mostly limited to potential request smuggling, where an intermediate proxy considers the data on the connection to be tunneled and the server considers it to be HTTP."
}
],
"lastModified": "2026-10-09T17:16:50.703",
"sourceIdentifier": "security@golang.org"
}