CVE-2023-39326 Denial of service via chunk extensions in net/http

2023-12-0616:27:53

www.cve.org

denial of service

chunk extensions

net/http

http sender

receiver

request

response body

network

malicious

client

server

data

handler

1gib

metadata

chunked encoding

error

ratio

real body

6.7 Medium

AI Score

Confidence

High

0.001 Low

EPSS

Percentile

20.6%

JSON

A malicious HTTP sender can use chunk extensions to cause a receiver reading from a request or response body to read many more bytes from the network than are in the body. A malicious HTTP client can further exploit this to cause a server to automatically read a large amount of data (up to about 1GiB) when a handler fails to read the entire body of a request. Chunk extensions are a little-used HTTP feature which permit including additional metadata in a request or response body sent using the chunked encoding. The net/http chunked encoding reader discards this metadata. A sender can exploit this by inserting a large metadata segment with each byte transferred. The chunk reader now produces an error if the ratio of real body to encoded bytes grows too small.

CNA Affected

[
  {
    "vendor": "Go standard library",
    "product": "net/http/internal",
    "collectionURL": "https://pkg.go.dev",
    "packageName": "net/http/internal",
    "versions": [
      {
        "version": "0",
        "lessThan": "1.20.12",
        "status": "affected",
        "versionType": "semver"
      },
      {
        "version": "1.21.0-0",
        "lessThan": "1.21.5",
        "status": "affected",
        "versionType": "semver"
      }
    ],
    "programRoutines": [
      {
        "name": "chunkedReader.beginChunk"
      },
      {
        "name": "readChunkLine"
      },
      {
        "name": "chunkedReader.Read"
      }
    ],
    "defaultStatus": "unaffected"
  }
]