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CVE-2026-40296

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CVE-2026-40296

Published: May 6, 2026

Modified: May 7, 2026

PUBLISHED

CVSS v3.1

5.4

MEDIUM

Description

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.

VendorProductVersions

PHPOffice

PhpSpreadsheet

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

Weaknesses (CWE)

CWE-79

CVSS v3.1 Details

CVSS v3.1 Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

References

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