zeromq3 — security advisory

{
  "id": "cb9c08eb2937f45071504079643f5471e4d7b8722122558932397ce0b20d2e66",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2021-20236",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2021-20236",
    "summary": "A flaw was found in the ZeroMQ server in versions before 4.3.3. This flaw allows a malicious client to cause a stack buffer overflow on the server by sending crafted topic subscription requests and then unsubscribing. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.",
    "evidence": "osv:DEBIAN-CVE-2021-20236",
    "products": [
      {
        "name": {
          "value": "zeromq3",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "4.3.3-1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "zeromq3",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "4.3.3-1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "zeromq3",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "4.3.3-1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "DEBIAN-CVE-2021-20236",
      "aliases": [
        "DEBIAN-CVE-2021-20236"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "4.3.3-1"
                }
              ]
            }
          ],
          "package": {
            "name": "zeromq3",
            "purl": "pkg:deb/debian/zeromq3?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-20236.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "4.3.3-1"
                }
              ]
            }
          ],
          "package": {
            "name": "zeromq3",
            "purl": "pkg:deb/debian/zeromq3?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-20236.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "4.3.3-1"
                }
              ]
            }
          ],
          "package": {
            "name": "zeromq3",
            "purl": "pkg:deb/debian/zeromq3?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-20236.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-23T18:04:48.813382139Z",
      "provider": "osv",
      "upstream": [
        "CVE-2021-20236"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2021-20236"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2021-20236",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 423913,
  "published_at": "2021-05-28T11:15:07.933+00:00"
}