Security advisory

{
  "id": "3fb419d40fa61e51e2d062d1bcfa426c7fb7cbed4d34d259162e3b03e101257d",
  "url": "https://osv.dev/vulnerability/CVE-2026-76957",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2026-76957",
    "summary": "libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.",
    "evidence": "osv:CVE-2026-76957",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-76957",
      "aliases": [
        "CVE-2026-76957"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/libexpat/libexpat",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "12cf0b1f25f026a022fe728ad8f7e3d017285b80"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.8.4"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "cpe": "cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.8.4"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "R_2_8_3",
            "R_2_8_2",
            "R_2_8_1",
            "R_2_8_0",
            "R_2_7_5",
            "R_2_7_4",
            "R_2_7_3",
            "R_2_7_2",
            "R_2_7_1",
            "R_2_7_0",
            "R_2_6_4",
            "R_2_6_3",
            "R_2_6_2",
            "R_2_6_1",
            "R_2_6_0",
            "R_2_5_0",
            "R_2_4_9",
            "R_2_4_8",
            "R_2_4_7",
            "R_2_4_6",
            "R_2_4_5",
            "R_2_4_4",
            "R_2_4_3",
            "R_2_4_2",
            "R_2_4_1",
            "R_2_4_0",
            "R_2_3_0",
            "R_2_2_10",
            "R_2_2_9",
            "R_2_2_8",
            "R_2_2_7",
            "R_2_2_6",
            "R_2_2_5",
            "R_2_2_4",
            "R_2_2_3",
            "R_2_2_2",
            "R_2_2_1",
            "R_2_2_0",
            "R_2_1_1",
            "R_2_1_0",
            "R_2_0_1",
            "R_2_0_0",
            "R_1_95_8",
            "R_1_95_7",
            "R_1_95_6",
            "R_1_95_5",
            "R_1_95_4",
            "R_1_95_3",
            "R_1_95_2",
            "R_1_95_0",
            "libexpat-alpha-1",
            "start",
            "sourceforge_init",
            "jclark-orig",
            "V20000512",
            "V19991013",
            "V19990728",
            "V19990709",
            "V19990626",
            "V1_1",
            "V19990425",
            "V1990307",
            "V19990109",
            "V19981231",
            "V19981122",
            "V1_0",
            "beta4",
            "beta3",
            "beta2",
            "REC1_0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-76957.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.300133011Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/76xxx/CVE-2026-76957.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-76957",
        "https://github.com/libexpat/libexpat/pull/1322",
        "https://github.com/libexpat/libexpat/pull/1329"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-416"
        ],
        "cna_assigner": "mitre",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/76xxx/CVE-2026-76957.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-76957",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 497298,
  "published_at": "2026-08-20T04:28:04.788+00:00"
}