{"id":"CVE-2026-93753","summary":"deepmerge through 4.3.1 Prototype Poisoning via mergeObject","details":"deepmerge through 4.3.1 contains a prototype poisoning vulnerability in the mergeObject() function that fails to properly validate keys being written to target objects. Attackers can supply malicious source objects in merge operations to inject attacker-controlled properties into the returned object's prototype, causing applications to inherit unintended values when accessing properties without own-property checks.","modified":"2026-09-20T11:47:30.172710323Z","published":"2026-09-18T17:51:37.794Z","database_specific":{"cna_assigner":"VulnCheck","cwe_ids":["CWE-1321"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93753.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93753.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93753"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/deepmerge-through-4.3.1-prototype-poisoning-via-mergeobject"},{"type":"REPORT","url":"https://github.com/TehShrike/deepmerge/issues/273"},{"type":"PACKAGE","url":"https://github.com/TehShrike/deepmerge"},{"type":"ARTICLE","url":"https://github.com/TehShrike/deepmerge/blob/5b87756a5671635679001cbac72aa42f23472c81/index.js#L39-L60"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/tehshrike/deepmerge","events":[{"introduced":"0"},{"fixed":"5b87756a5671635679001cbac72aa42f23472c81"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"last_affected":"4.3.1"},{"fixed":"4.3.1"}],"source":["AFFECTED_FIELD","DESCRIPTION"]}}],"versions":["v4.3.0","v4.2.2","v4.2.1","v4.2.0","v4.1.2","v4.0.0","v4.1.1","v4.1.0","v3.3.0","v3.2.1","v3.2.0","v3.1.0","v3.0.0","v2.2.1","v2.2.0","v2.1.1","v2.1.0","v2.0.1","v2.0.0","v1.5.2","v1.5.1","v1.5.0","v1.4.4","v1.4.3","v1.4.2","v1.4.1","v1.4.0","v1.3.2","v1.3.1","v1.3.0","v1.2.0","v1.1.1","v1.1.0","v1.0.3","v1.0.2","v1.0.1","v0.2.9","v0.2.8","v0.2.5","v0.2.4","v0.2.1","v0.2.0","v0.1.0","v0.0.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93753.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"}]}