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expat, libxmltok — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2021-45960

In Expat (aka libexpat) before 2.4.3, a left shift by 29 (or more) places in the storeAtts function in xmlparse.c can lead to realloc misbehavior (e.g., allocating too few bytes, or only freeing memory).

Products
expat, libxmltok
Affected versions
1.2-4, 1.2-4.1, 1.2-4.1~exp1, 1.2-4.2
Fixed versions
2.4.3-1
CVEs
CVE-2021-45960
Confirmed fixed CVEs
Not specified
Updated in this feed
30 Oct 2026, 16:39 UTC · Revision 1

Source evidence

DEBIAN-CVE-2021-45960

core-osv · Original source

Published 1 Jan 2022, 19:15 UTC

In Expat (aka libexpat) before 2.4.3, a left shift by 29 (or more) places in the storeAtts function in xmlparse.c can lead to realloc misbehavior (e.g., allocating too few bytes, or only freeing memory).

osv:DEBIAN-CVE-2021-45960

expat

Fixed versions: 2.4.3-1

expat

Fixed versions: 2.4.3-1

expat

Fixed versions: 2.4.3-1

libxmltok

Fixed versions: Not specified

Complete source record
{
  "id": "52eda9cc23084e7343861a71d2c88457b500dc5274289dcbcc798a3fce32f913",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2021-45960",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2021-45960",
    "summary": "In Expat (aka libexpat) before 2.4.3, a left shift by 29 (or more) places in the storeAtts function in xmlparse.c can lead to realloc misbehavior (e.g., allocating too few bytes, or only freeing memory).",
    "evidence": "osv:DEBIAN-CVE-2021-45960",
    "products": [
      {
        "name": {
          "value": "expat",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.4.3-1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "expat",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.4.3-1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "expat",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.4.3-1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "libxmltok",
          "evidence": "/affected/3/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.2-4",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "1.2-4.1",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "1.2-4.1~exp1",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "1.2-4.2",
            "evidence": "/affected/3/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "DEBIAN-CVE-2021-45960",
      "aliases": [
        "DEBIAN-CVE-2021-45960"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.4.3-1"
                }
              ]
            }
          ],
          "package": {
            "name": "expat",
            "purl": "pkg:deb/debian/expat?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-45960.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.4.3-1"
                }
              ]
            }
          ],
          "package": {
            "name": "expat",
            "purl": "pkg:deb/debian/expat?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-45960.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.4.3-1"
                }
              ]
            }
          ],
          "package": {
            "name": "expat",
            "purl": "pkg:deb/debian/expat?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-45960.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "libxmltok",
            "purl": "pkg:deb/debian/libxmltok?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "versions": [
            "1.2-4",
            "1.2-4.1",
            "1.2-4.1~exp1",
            "1.2-4.2"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-45960.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-15T09:47:36.120363525Z",
      "provider": "osv",
      "upstream": [
        "CVE-2021-45960"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2021-45960"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2021-45960",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 327880,
  "published_at": "2022-01-01T19:15:08.03+00:00"
}