Vulnerability GO-2026-6452

In github.com/xuri/excelize/v2, parsing a spreadsheet cell with a negative shared-string index causes a runtime panic. The shared-string lookup in xlsxC.getValueFrom checks only the upper bound of the parsed index against the shared-string slice length, causing negative indices (such as -1) to bypass validation and trigger an out-of-bounds slice access when reading cells via APIs such as GetCellValue or GetRows.