PhpSpreadsheet's XmlScanner::scan() uses a regex pattern that only accounts for NULL byte (0x00) interleaving when detecting <!DOCTYPE. ISO-2022 escape sequences (0x1B bytes) inserted between the characters of the pattern break the regex match entirely, allowing DOCTYPE declarations with entity definitions to pass through undetected. This enables Denial of Service via quadratic entity expansion on all PHP versions, and XXE/SSRF on PHP < 8.0 or when LIBXML_NOENT is used. Any application …
The SpreadsheetML XML reader (Reader\Xml) scans file content twice through XmlScanner::scan(), and each scan runs an unentity() callback that calls html_entity_decode() after the pattern check. By double-encoding the < character as &#60;, the first scan decodes & to & (forming <), and the second scan decodes < to < (forming <!DOCTYPE). Neither scan's pattern check detects the <!DOCTYPE string because the callback runs after each check. This enables Denial of …
PhpSpreadsheet's Worksheet\Drawing::setPath() validates an external-image URL against an operator-supplied isWhitelisted callback once, on the initial URL only, then fetches it with file_get_contents() using a stream context that does not set follow_location => 0. A whitelisted host that returns an HTTP 302 Location: redirect to an internal target is therefore followed by PHP's HTTP wrapper (default follow_location=1, max_redirects=20) with no re-validation of the redirect hop — defeating the whitelist and yielding …
When PhpSpreadsheet loads an OpenDocument Spreadsheet (.ods), Ods::processTableRow() reads the table:number-rows-repeated attribute of a <table:table-row> with an unchecked (int) cast, then materialises one cell per repeated row. This value is completely unbounded, so a single ~1.4 KB file can instruct the reader to create up to millions of cells, exhausting memory (fatal OOM). No authentication, no special configuration, and the default read filter are required - any application that loads …
PhpSpreadsheet's OLE reader follows sector chains from attacker-controlled XLS/OLE metadata without detecting cycles or enforcing a maximum chain length. A tiny malformed .xls/OLE file can set the small-block depot sector chain to point back to itself. During normal XLS detection, OLERead::read() appends the same sector data repeatedly until the PHP process exhausts memory. This is reachable from Reader\Xls::canRead() and therefore from automatic spreadsheet type detection. Applications that accept attacker-controlled spreadsheet …
The domain whitelist introduced in PhpSpreadsheet 5.4.0 for the WEBSERVICE() formula function can be bypassed via HTTP redirect. The whitelist validates only the initial URL's hostname, but file_get_contents() follows 302/301 redirects by default without re-validating the redirect target against the whitelist. This allows an attacker to reach internal services through a whitelisted domain that issues an HTTP redirect.
PhpSpreadsheet's Gnumeric reader reads attacker-supplied .gnumeric files into memory and, when the file starts with gzip magic bytes, calls gzdecode() on the full compressed contents without enforcing a decompressed-size limit. A very small compressed .gnumeric file can expand to data larger than the PHP memory limit and crash the process during Gnumeric::canRead() before the file is rejected or fully parsed. This is reachable through normal file-type detection and Gnumeric loading …
CVE-2026-34084 was patched by the helper File::prohibitWrappers. The helper calls parse_url($filename, PHP_URL_SCHEME) and then checks is_string($scheme) && strlen($scheme) > 1 to reject stream wrappers such as phar://, php://, data:// or expect://. The check is not equivalent to "does the path contain a wrapper". When the input has the form phar:///path/file.phar/inner with three or more slashes after the scheme, parse_url returns boolean false instead of returning the scheme string. The is_string($scheme) …
The usage of is_file, used to verify if the $filename is indeed an actual file, by all(?) Reader implementations (inside the helper function File::assertFile) is php-wrapper aware, for any php wrappers implementing stat(). The 3 wrappers ftp://, phar:// and ssh2.sftp://, all satisfy this requirement - 2 of which are shown in the PoC below. This results in a SSRF, at "best", and RCE at worse. This was tested against the …
The XLSX reader's ColumnAndRowAttributes::readRowAttributes() method reads row numbers from XML attributes without validating them against the spreadsheet maximum row limit (AddressRange::MAX_ROW = 1,048,576). An attacker can craft a minimal XLSX file (~1.6KB) containing a <row r="999999999"/> element that inflates cachedHighestRow to 999,999,999, causing any subsequent row iteration to attempt ~1 billion loop cycles and exhaust CPU resources.
The SpreadsheetML XML reader (Reader\Xml) does not validate the ss:Index row attribute against the maximum allowed row count (AddressRange::MAX_ROW = 1,048,576). An attacker can craft a SpreadsheetML XML file with ss:Index="999999999" on a <Row> element, which inflates the internal cachedHighestRow to ~1 billion. Any subsequent call to getRowIterator() without an explicit end row will attempt to iterate ~1 billion rows, causing CPU exhaustion and denial of service.
The HTML Writer in PhpSpreadsheet bypasses htmlspecialchars() output escaping when a cell uses a custom number format containing the @ text placeholder with additional literal text (e.g., @ "items" or "Total: "@). This allows an attacker to inject arbitrary HTML and JavaScript into the generated HTML output by crafting a malicious XLSX file.
It was discovered that there is a way to bypass HTML escaping in the HTML writer using custom number format codes.