CVE-2026-35453

Summary

PhpSpreadsheet is a library for reading and writing spreadsheet files. In versions 1.30.3 and earlier, 2.0.0 through 2.1.15, 2.2.0 through 2.4.4, 3.3.0 through 3.10.4, and 4.0.0 through 5.6.0, the HTML Writer skips htmlspecialchars() output escaping when a cell uses a custom number format containing the @ text placeholder with additional literal text (e.g., @ "items"). The escaping is only applied when the formatted output strictly equals the original cell value. When the format code contains @ with quoted literal text, the formatter substitutes the raw cell value into the format string and returns early without invoking the escaping callback. An attacker who can control cell content in a spreadsheet processed by the HTML Writer can inject arbitrary HTML and JavaScript into the generated output. This issue has been fixed in versions 1.30.4, 2.1.16, 2.4.5, 3.10.5, and 5.7.0.

Affected Software

VendorProductVersion RangeStatus
PHPOfficePhpSpreadsheet>= 4.0.0, <= 5.6.0affected
PHPOfficePhpSpreadsheet>= 3.3.0, <= 3.10.4affected
PHPOfficePhpSpreadsheet>= 2.2.0, <= 2.4.4affected
PHPOfficePhpSpreadsheet>= 2.0.0, <= 2.1.15affected
PHPOfficePhpSpreadsheet<= 1.30.3affected

Weaknesses

  • CWE-79: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: poc
    • Automatable: no
    • Technical Impact: partial

Additional References

References