PhpSpreadsheet: XmlScanner Bypass via Double-Encoded unentity() TOCTOU Allows XXE and Denial of Service
PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. From 3.3.0 until 3.10.8 and 5.10.0, Reader\Xml passes stored SpreadsheetML XML through XmlScanner::scan in Xml::canRead and Xml::trySimpleXMLLoadStringPrivate, while Xml::unentity decodes numeric entities only after each DOCTYPE pattern check. A double-encoded less-than character is reduced by the first callback to another encoded character and by the second callback to a literal less-than sign, so SimpleXML receives an unchecked DOCTYPE and entity declaration. Processing attacker-controlled SpreadsheetML XML can cause entity-expansion denial of service and can permit local file access or SSRF on PHP before 8.0 or when LIBXML_NOENT is enabled. This issue is fixed in versions 3.10.8 and 5.10.0.
CVE-2026-108357
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-108357
PhpSpreadsheet
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"vendor": "PHPOffice",
"product": "PhpSpreadsheet",
"versions": [
{
"status": "affected",
"version": ">= 3.3.0, < 3.10.8"
},
{
"status": "affected",
"version": ">= 4.0.0, < 5.10.0"
}
]
}
]- Related CVEs
- CVE-2026-108357
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #53256 · Revision 1
- Added to Heist Feed
- Publisher date