Summary
Excelize ColumnNameToNumber: int64 overflow yields an out-of-domain coordinate with nil error, causing negative slice index panic on r="0" rows
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).
When 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.
Details
- The row side of the same coordinate gate is enforced (
checkRowNumat excelize.go:342-350 boundsrbefore themake([]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/checkSheetR0treaterr == nilfromCellNameToCoordinatesas proof of an in-domain coordinate (excelize.go:356, :438), which is unsound because of the wrap-around above. - The same unsound gate also feeds
ws.SheetData.Row[rowIdx].C[colNum-1]inxlsxWorksheet.checkRow(rows.go:969): a row combining a valid large column (e.g.XFD1) with an overflowed column panics identically. - Reachable from any
workSheetReader-based API on an attacker-supplied worksheet:GetCellValue,GetCellFormula,SetCellValue,GetMergeCells,GetSheetDimension,GetColWidth,AddTable, etc. - Probe on pristine master:
ColumnNameToNumber("VGWQHXLSDVIKWV")returns(0, nil). - 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.
PoC
A 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.
Proposed fix
Bound 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.
Impact
A <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.
An arithmetic operation produces a value that exceeds the integer type's maximum, causing it to wrap to an unexpected small value. Typical impact: incorrect size calculations leading to heap overflows or logic errors.
CVE-2026-107217 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.11.1-0.20260910071107-696050fbf14e); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Frequently Asked Questions
- What is CVE-2026-107217? CVE-2026-107217 is a high-severity integer overflow or wraparound vulnerability in github.com/xuri/excelize/v2 (go), affecting versions >= 2.0.0, < 2.11.1-0.20260910071107-696050fbf14e. It is fixed in 2.11.1-0.20260910071107-696050fbf14e. An arithmetic operation produces a value that exceeds the integer type's maximum, causing it to wrap to an unexpected small value.
- How severe is CVE-2026-107217? CVE-2026-107217 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which packages are affected by CVE-2026-107217?
github.com/xuri/excelize/v2(go) (versions >= 2.0.0, < 2.11.1-0.20260910071107-696050fbf14e)github.com/xuri/excelize(go) (versions >= 1.1.0, <= 1.4.1)
- Is there a fix for CVE-2026-107217? Yes. CVE-2026-107217 is fixed in 2.11.1-0.20260910071107-696050fbf14e. Upgrade to this version or later.
- Is CVE-2026-107217 exploitable, and should I be worried? Whether CVE-2026-107217 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-107217 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-107217? Upgrade
github.com/xuri/excelize/v2to 2.11.1-0.20260910071107-696050fbf14e or later.