CVE-2026-35453: PhpSpreadsheet XSS via number format text substitution in HTML Writer
PHPOffice · PhpSpreadsheet
Affected: PHPOffice PhpSpreadsheet · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 10% of scored CVEs
DescriptionCVE.org
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 products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- PHPOffice · PhpSpreadsheet>= 4.0.0, <= 5.6.0; >= 3.3.0, <= 3.10.4; >= 2.2.0, <= 2.4.4; >= 2.0.0, <= 2.1.15; <= 1.30.3
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Weakness
- Cross-site Scripting
- Vendor
- PHPOffice
- Published
- May 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-35453 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.