zeromq3 — security advisory

{
  "id": "825b32e0b392fb9c118d805eb1146b7ea3b1b65e3677076511d96b789536372f",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2021-20235",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2021-20235",
    "summary": "There's a flaw in the zeromq server in versions before 4.3.3 in src/decoder_allocators.hpp. The decoder static allocator could have its sized changed, but the buffer would remain the same as it is a static buffer. A remote, unauthenticated attacker who sends a crafted request to the zeromq server could trigger a buffer overflow WRITE of arbitrary data if CURVE/ZAP authentication is not enabled. The greatest impact of this flaw is to application availability, data integrity, and confidentiality.",
    "evidence": "osv:DEBIAN-CVE-2021-20235",
    "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": "high",
    "structured": {
      "id": "DEBIAN-CVE-2021-20235",
      "aliases": [
        "DEBIAN-CVE-2021-20235"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/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-2021-20235.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-2021-20235.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-2021-20235.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-23T18:04:48.840746131Z",
      "provider": "osv",
      "upstream": [
        "CVE-2021-20235"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2021-20235"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2021-20235",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 423917,
  "published_at": "2021-04-01T14:15:13.217+00:00"
}