CVE-2026-40296

Summary

PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. The HTML writer skips htmlspecialchars escaping when a cell's formatted value differs from the original value. When a cell has a custom number format containing the text placeholder @ along with any additional literal characters (for example ". @", "@ ", or "x@"), the formatter replaces @ with the cell value and adds the extra characters, causing the formatted value to differ from the original and bypassing HTML escaping entirely. An attacker who can control the cell value and number format of an uploaded spreadsheet that is later converted to HTML and displayed to other users can achieve stored cross-site scripting. This issue is fixed in versions 5.7.0, 3.10.5, 2.4.5, 2.1.16, and 1.30.4.

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