CVE-2026-110600

xlsxio through 0.2.37 contains a NULL pointer dereference vulnerability in main_sheet_get_sheetfile_expat_callback_element_start() in lib/xlsxio_read.c that allows attackers to crash applications via crafted files. Attackers can supply a .xlsx file whose workbook.xml.rels contains a worksheet Relationship lacking an Id attribute, crashing the process when xlsxioread_sheet_open() is called.

• https://github.com/brechtsanders/xlsxio/blob/0.2.37/lib/xlsxio_read.c#L851-L866
• https://github.com/brechtsanders/xlsxio/issues/151
• https://hackmd.io/@haind-pwn/xlsxio-relationship-missing-id-null-deref
• https://www.vulncheck.com/advisories/xlsxio-through-0.2.37-null-pointer-dereference-via-worksheet-relationship-without-id
• https://github.com/brechtsanders/xlsxio/issues/151
• https://hackmd.io/@haind-pwn/xlsxio-relationship-missing-id-null-deref