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HTTP/2 transport accepts malformed framing-related headers in net/http

Type: advisorySource: Official CVE List1 source record

Historically, we have been rather lax about malformed framing-related headers in our HTTP/2 implementation, as they cannot interfere with HTTP/2 framing. However, this makes it possible for our HTTP/2 implementation to forward responses containing such headers to an HTTP/1 client when acting as a reverse proxy. If the HTTP/1 client also does not behave strictly enough, this can result in response smuggling.

Announced Source revision 1
Original source ↗

CVE-2026-78660

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-78660

net/http

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

net/http/internal/http2

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

golang.org/x/net/http2

Source reference: /containers/cna/affected/2/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "vendor": "Go standard library",
    "product": "net/http",
    "versions": [
      {
        "status": "affected",
        "version": "0",
        "lessThan": "1.26.9",
        "versionType": "semver"
      }
    ],
    "packageName": "net/http",
    "collectionURL": "https://pkg.go.dev",
    "defaultStatus": "unaffected",
    "programRoutines": [
      {
        "name": "http2clientConnReadLoop.handleResponse"
      },
      {
        "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"
      },
      {
        "name": "http2Transport.NewClientConn"
      },
      {
        "name": "http2Transport.RoundTrip"
      },
      {
        "name": "http2Transport.RoundTripOpt"
      },
      {
        "name": "http2clientConnPool.GetClientConn"
      },
      {
        "name": "http2noDialClientConnPool.GetClientConn"
      },
      {
        "name": "http2noDialH2RoundTripper.NewClientConn"
      },
      {
        "name": "http2noDialH2RoundTripper.RoundTrip"
      },
      {
        "name": "http2unencryptedTransport.RoundTrip"
      }
    ]
  },
  {
    "vendor": "Go standard library",
    "product": "net/http/internal/http2",
    "versions": [
      {
        "status": "affected",
        "version": "1.27.0-0",
        "lessThan": "1.27.2",
        "versionType": "semver"
      }
    ],
    "packageName": "net/http/internal/http2",
    "collectionURL": "https://pkg.go.dev",
    "defaultStatus": "unaffected",
    "programRoutines": [
      {
        "name": "clientConnReadLoop.handleResponse"
      },
      {
        "name": "Transport.AddConn"
      },
      {
        "name": "Transport.NewClientConn"
      },
      {
        "name": "Transport.RoundTrip"
      },
      {
        "name": "Transport.RoundTripOpt"
      },
      {
        "name": "clientConnPool.GetClientConn"
      },
      {
        "name": "noDialClientConnPool.GetClientConn"
      }
    ]
  },
  {
    "vendor": "golang.org/x/net",
    "product": "golang.org/x/net/http2",
    "versions": [
      {
        "status": "affected",
        "version": "0",
        "lessThan": "0.60.0",
        "versionType": "semver"
      }
    ],
    "packageName": "golang.org/x/net/http2",
    "collectionURL": "https://pkg.go.dev",
    "defaultStatus": "unaffected",
    "programRoutines": [
      {
        "name": "clientConnReadLoop.handleResponse"
      },
      {
        "name": "Transport.NewClientConn"
      },
      {
        "name": "Transport.RoundTrip"
      },
      {
        "name": "Transport.RoundTripOpt"
      },
      {
        "name": "clientConnPool.GetClientConn"
      },
      {
        "name": "noDialClientConnPool.GetClientConn"
      },
      {
        "name": "noDialH2RoundTripper.NewClientConn"
      },
      {
        "name": "noDialH2RoundTripper.RoundTrip"
      },
      {
        "name": "unencryptedTransport.RoundTrip"
      }
    ]
  }
]
Related CVEs
CVE-2026-78660

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#16342 · Revision 1
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Publisher date
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