Excelize: Unbounded <col max> attribute is loaded with no MaxColumns check and expanded per-column by flatCols(), so any column mutator hangs or OOMs the process

Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. From 2.1.0 to 2.11.0, flatCols expands file-loaded column ranges without validating Min and Max against the worksheet column limit. SetColWidth reaches flatCols, which expands xlsxCol.Min through xlsxCol.Max without enforcing MaxColumns. When a crafted worksheet supplies an oversized col max attribute and the application invokes a column mutator, flatCols performs a deep copy and append for every attacker-selected column number, allowing an attacker to consume excessive CPU and memory or trigger OOM. No fixed version is available as of this review.

Source published

7 Oct 2026 18:48:54 UTC

Source modified

7 Oct 2026 22:05:27 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 7.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N