{"cve":"CVE-2026-40296","nvd":{"published":"2026-05-06T22:16:25.510","modified":"2026-10-26T19:10:00.163","status":"Analyzed","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","score":5.4},"cwes":["CWE-79"],"references":["https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-hrmw-qprp-wgmc","https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-hrmw-qprp-wgmc"],"products":["phpoffice:phpspreadsheet"],"source":"nvd","synced_at":"2026-10-26T19:31:02.781428341+00:00"},"epss":{"cve":"CVE-2026-40296","score":0.00225,"percentile":0.13046,"date":"2026-10-26"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}