HTML Injection Vulnerability in PhpSpreadsheet by PHPOffice
CVE-2026-35453

4.8MEDIUM

Key Information:

Vendor

PHPoffice

Status
PHPspreadsheet
Vendor
CVE Published:
5 May 2026

What is CVE-2026-35453?

A vulnerability exists in PhpSpreadsheet's HTML Writer component that allows attackers to inject arbitrary HTML and JavaScript if they can manipulate the content of a cell with a specific custom number format. The issue arises due to inadequate output escaping when the custom format includes the '@' text placeholder alongside additional literal text. The vulnerability has been addressed in the latest versions, ensuring that appropriate escaping is applied to prevent the injection of malicious content.

Affected Version(s)

PhpSpreadsheet >= 4.0.0, <= 5.6.0 <= 4.0.0, 5.6.0

PhpSpreadsheet >= 3.3.0, <= 3.10.4 <= 3.3.0, 3.10.4

PhpSpreadsheet >= 2.2.0, <= 2.4.4 <= 2.2.0, 2.4.4

References

https://github.com/PHPOffice/PhpSpreadsheet/security/advi...
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CVSS V4

Score:
4.8
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.