Security advisory

{
  "id": "761523d1eda6a0417a396950f33244342af0b2e908d49d1493afa108cf5013d8",
  "url": "https://osv.dev/vulnerability/CVE-2018-1000027",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2018-1000027",
    "summary": "The Squid Software Foundation Squid HTTP Caching Proxy version prior to version 4.0.23 contains a NULL Pointer Dereference vulnerability in HTTP Response X-Forwarded-For header processing that can result in Denial of Service to all clients of the proxy. This attack appear to be exploitable via Remote HTTP server responding with an X-Forwarded-For header to certain types of HTTP request. This vulnerability appears to have been fixed in 4.0.23 and later.",
    "evidence": "osv:CVE-2018-1000027",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2018-1000027",
      "aliases": [
        "CVE-2018-1000027"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/squid-cache/squid",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "787b41c3b0ef9b7330032a1947c5f93bd050f32a"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.0.23"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "SQUID_4_0_22",
            "SQUID_4_0_21",
            "SQUID_4_0_20",
            "SQUID_4_0_19",
            "SQUID_4_0_18",
            "SQUID_4_0_17",
            "SQUID_4_0_16",
            "SQUID_4_0_15",
            "SQUID_4_0_14",
            "SQUID_4_0_13",
            "SQUID_4_0_12",
            "SQUID_4_0_11",
            "SQUID_4_0_10",
            "SQUID_4_0_9",
            "SQUID_4_0_8",
            "SQUID_4_0_7",
            "SQUID_4_0_6",
            "SQUID_4_0_5",
            "SQUID_4_0_4",
            "SQUID_4_0_3",
            "SQUID_4_0_2",
            "SQUID_4_0_1",
            "take00",
            "SQUID_3_0_RC1",
            "SQUID_3_0_PRE7",
            "SQUID_3_0_PRE6",
            "SQUID_3_0_PRE5",
            "SQUID_3_0_PRE4",
            "SQUID_3_0_PRE3",
            "SQUID_3_0_PRE2",
            "SQUID_3_0_PRE1",
            "HISTORIC_RELEASES"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2018-1000027.json"
          }
        }
      ],
      "modified": "2026-10-20T10:50:12.944809679Z",
      "provider": "osv",
      "references": [
        "https://usn.ubuntu.com/4059-2/",
        "https://github.com/squid-cache/squid/pull/129/files",
        "https://lists.debian.org/debian-lts-announce/2018/02/msg00001.html",
        "https://lists.debian.org/debian-lts-announce/2018/02/msg00002.html",
        "https://usn.ubuntu.com/3557-1/",
        "https://www.debian.org/security/2018/dsa-4122"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*",
              "cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*",
              "cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:*"
            ],
            "vendor_product": "canonical:ubuntu_linux",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "14.04"
                  },
                  {
                    "last_affected": "14.04"
                  },
                  {
                    "introduced": "16.04"
                  },
                  {
                    "last_affected": "16.04"
                  },
                  {
                    "introduced": "17.10"
                  },
                  {
                    "last_affected": "17.10"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          },
          {
            "cpes": [
              "cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*",
              "cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*",
              "cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*"
            ],
            "vendor_product": "debian:debian_linux",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "7.0"
                  },
                  {
                    "last_affected": "7.0"
                  },
                  {
                    "introduced": "8.0"
                  },
                  {
                    "last_affected": "8.0"
                  },
                  {
                    "introduced": "9.0"
                  },
                  {
                    "last_affected": "9.0"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2018-1000027",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 381402,
  "published_at": "2018-02-09T23:29:00.87+00:00"
}