CRITICALVulnerability
CVE-2026-78207
exceljs through 4.4.0 contains a prototype pollution vulnerability in the deepMerge helper that fails to reject __proto__, constructor, or prototype keys when merging note objects. Attackers can assign parsed JSON with a malicious __proto__ property to cell notes, modifying Object.prototype and affecting all plain objects created in the process.
Properties
- severity
- CRITICAL
- score
- 9.4
- cve_id
- CVE-2026-78207
- vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
- published_at
- 2026-08-24T01:16:58.137
- last_modified
- 2026-08-31T20:52:56.343
Related Entities (2)
DESCRIBED_BY (1)
→[Source]NVD
HAS_WEAKNESS (1)
→[Weakness]Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
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