CVE-2026-107217: Excelize ColumnNameToNumber Int64 Overflow Yields An Out-of-domain Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-c85p-xxjj-2r75",
  "modified" : "2026-10-07T20:23:31Z",
  "published" : "2026-10-07T20:23:31Z",
  "aliases" : [ "CVE-2026-107217" ],
  "summary" : "Excelize ColumnNameToNumber: int64 overflow yields an out-of-domain coordinate with nil error, causing negative slice index panic on r=\"0\" rows",
  "details" : "### Summary\n\n`ColumnNameToNumber` (lib.go:220-237) accumulates the bijective base-26 value of a column name in an int64 with only an upper-bound check (`col > MaxColumns`) applied after the loop and no overflow detection. A 14-letter column name whose true value is 3·2⁶⁴ — e.g. **`VGWQHXLSDVIKWV`** — wraps to `col = 0` and passes the guard, so `CellNameToCoordinates(\"VGWQHXLSDVIKWV1\")` returns `(col=0, row=1, err=nil)`.\n\nWhen normalizing a `r=\"0\"` row, `checkSheetR0` (excelize.go:417-443, called from `checkSheet` at excelize.go:405) runs its `checkRow` closure with `col = 0`: `colIdx := col - 1` becomes **-1**, and `sheetData.Row[rowIdx].C[-1]` (excelize.go:424) raises an unrecovered `panic: runtime error: index out of range [-1]`, killing the host process.\n\n### Details\n\n- The row side of the same coordinate gate is enforced (`checkRowNum` at excelize.go:342-350 bounds `r` before the `make([]xlsxRow, row)` allocation; this includes the fix for GHSA-h69g-9hx6-f3v4 / CVE-2026-54063, present in the audited commit). The **column** side is not: `checkSheet`/`lastRowNum`/`checkSheetR0` treat `err == nil` from `CellNameToCoordinates` as proof of an in-domain coordinate (excelize.go:356, :438), which is unsound because of the wrap-around above.\n- The same unsound gate also feeds `ws.SheetData.Row[rowIdx].C[colNum-1]` in `xlsxWorksheet.checkRow` (rows.go:969): a row combining a valid large column (e.g. `XFD1`) with an overflowed column panics identically.\n- Reachable from any `workSheetReader`-based API on an attacker-supplied worksheet: `GetCellValue`, `GetCellFormula`, `SetCellValue`, `GetMergeCells`, `GetSheetDimension`, `GetColWidth`, `AddTable`, etc.\n- Probe on pristine master: `ColumnNameToNumber(\"VGWQHXLSDVIKWV\")` returns `(0, nil)`.\n- This is a distinct root cause from GHSA-h69g-9hx6-f3v4 (row-index allocation): different mechanism (int64 wrap-around → negative index, not oversized allocation), different sink, different fix.\n\n### PoC\n\nA standalone program (public API only) was provided to the maintainer by email (`3-column-overflow`): it builds a workbook in memory whose `xl/worksheets/sheet1.xml` contains `<sheetData><row r=\"0\"><c r=\"VGWQHXLSDVIKWV1\" t=\"inlineStr\"><is><t>pwn</t></is></c></row></sheetData>` (<1 KB of attacker XML), calls `OpenReader`, then `GetCellValue(\"Sheet1\", \"A1\")` → `PANIC_REPRODUCED: runtime error: index out of range [-1]` on master `ecd99d761fe0` (2026-09-08). With the proposed patch the same program prints `NO_PANIC_BLOCKED`.\n\n### Impact\n\nA <1 KB crafted `.xlsx` crashes any service that opens a user-supplied spreadsheet and reads it — upload processing, mail-scanning pipelines, spreadsheet conversion endpoints. Remote, unauthenticated, no privileges.\n\n### Proposed fix\n\nBound the accumulated value inside the loop: check `col > MaxColumns` after each digit. Every digit is at least 1, so any name whose true value exceeds MaxColumns crosses the bound inside the loop, before the accumulation can wrap or overflow — this provably covers all cases, including wraps that would land back inside `[1, MaxColumns]`. A complete patch has been provided to the maintainer.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/xuri/excelize/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "fixed" : "2.11.1-0.20260910071107-696050fbf14e"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/xuri/excelize"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.1.0"
      }, {
        "last_affected" : "1.4.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/qax-os/excelize/security/advisories/GHSA-c85p-xxjj-2r75"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/qax-os/excelize/pull/2394"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/qax-os/excelize/commit/696050fbf14e74e96a58eef2b16aaf72f381a6a8"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/qax-os/excelize"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-129", "CWE-190" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-07T20:23:31Z",
    "nvd_published_at" : null
  }
}