Excelize: Panic in cellInRange on a worksheet with an empty mergeCell ref

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. From 2.7.1 to 2.11.0, mergeCellsParser leaves the cached rectangle empty for an empty mergeCell ref and then passes that empty slice to cellInRange without a length check. GetCellValue reaches mergeCellsParser, which passes an empty rectangle derived from the mergeCell ref attribute into cellInRange. When a crafted worksheet contains an empty mergeCell ref and a non-streaming cell API reads the worksheet, cellInRange indexes four positions in an empty slice, allowing an attacker to panic on the first affected cell operation. No fixed version is available as of this review.

Source published

7 Oct 2026 18:37:52 UTC

Source modified

10 Oct 2026 02:41:14 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. From 2.7.1 to 2.11.0, mergeCellsParser leaves the cached rectangle empty for an empty mergeCell ref and then passes that empty slice to cellInRange without a length check. GetCellValue reaches mergeCellsParser, which passes an empty rectangle derived from the mergeCell ref attribute into cellInRange. When a crafted worksheet contains an empty mergeCell ref and a non-streaming cell API reads the worksheet, cellInRange indexes four positions in an empty slice, allowing an attacker to panic on the first affected cell operation. No fixed version is available as of this review.

Source published

Oct 7, 2026, 6:37:52 PM (timezone not stated)

Source modified

Oct 10, 2026, 2:41:14 AM (timezone not stated)

Observed here

9 Nov 2026 05:07:26 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. From 2.7.1 to 2.11.0, mergeCellsParser leaves the cached rectangle empty for an empty mergeCell ref and then passes that empty slice to cellInRange without a length check. GetCellValue reaches mergeCellsParser, which passes an empty rectangle derived from the mergeCell ref attribute into cellInRange. When a crafted worksheet contains an empty mergeCell ref and a non-streaming cell API reads the worksheet, cellInRange indexes four positions in an empty slice, allowing an attacker to panic on the first affected cell operation. No fixed version is available as of this review.

Source published

7 Oct 2026 19:17:34 UTC

Source modified

13 Oct 2026 14:23:03 UTC

Observed here

25 Oct 2026 04:17:41 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

### Summary A worksheet containing `<mergeCell ref=""/>` makes `mergeCellsParser` leave the cached rectangle empty, and `cellInRange` then indexes that empty slice without a length check. Every non-streaming cell API panics with `index out of range [0] with length 0` on the first cell read after opening the file. ### Where it is `cell.go`, `cellInRange` func cellInRange(cell, ref []int) bool { return cell[0] >= ref[0] && cell[0] <= ref[2] && cell[1] >= ref[1] && cell[1] <= ref[3] } `ref` is indexed at four positions with no bounds check. The caller that can hand it an empty slice, `mergeCellsParser` if ref := ws.MergeCells.Cells[i].Ref; len(ws.MergeCells.Cells[i].rect) == 0 && ref != "" { if strings.Count(ref, ":") != 1 { ref += ":" + ref } rect, err := rangeRefToCoordinates(ref) if err != nil { return cell, err } _ = sortCoordinates(rect) ws.MergeCells.Cells[i].rect = rect } if cellInRange([]int{col, row}, ws.MergeCells.Cells[i].rect) { The `ref != ""` condition means an empty `ref` skips the block that populates `rect`, so `rect` stays nil. The `cellInRange` call on the next line is unconditional and receives that nil slice. `Ref` comes straight from `xl/worksheets/sheetN.xml` through `encoding/xml`, so an empty string is entirely attacker-controlled. ### Impact Any consumer that opens an untrusted workbook and reads a cell panics. The loop scans every merged cell, so any cell reference triggers it, not a specific one. Affected entry points include `GetCellValue`, `GetCellType`, `GetCellFormula`, `SetCellValue` and the in-cell branch of `GetPictures`. The streaming `Rows` and `GetRows` use the SAX path and do not go through this parser, and `GetMergeCells` routes through `Rect()` which errors cleanly, which is probably why this has not surfaced before. There is no option or flag involved; opening the file succeeds and the panic fires on the first cell read. Unless the caller wraps the call in `recover()` it takes the process down. This is a regression. Commit a34c81e (PR #1500, 2023-03-20) replaced `checkCellInRangeRef`, whose `len(rng) != 2` guard returned cleanly for an empty ref, with the cached-rect fast path above, and the guard did not come along. `git merge-base --is-ancestor` confirms that commit is an ancestor of v2.11.0, so released versions are affected as well as HEAD. ### Proof of concept Executed at HEAD. Build a minimal xlsx whose `xl/worksheets/sheet1.xml` contains: <mergeCells count="1"><mergeCell ref=""></mergeCell></mergeCells> Then: f, err := excelize.OpenReader(bytes.NewReader(data)) if err != nil { t.Fatal(err) } _, _ = f.GetCellValue("Sheet1", "A1") Observed, running against the repository at HEAD: panic: runtime error: index out of range [0] with length 0 excelize.cellInRange cell.go:1691 excelize.(*xlsxWorksheet).mergeCellsParser cell.go:1660 excelize.(*File).getCellStringFunc cell.go:1512 excelize.(*File).GetCellValue cell.go:72 `OpenReader` itself returns no error; the file is 1656 bytes. A1, B1 and A2 all reproduce it. For context on how targeted this is, I ran a battery of 38 crafted files covering data validation, conditional formatting, cell and row references, number formats, cols, hyperlinks, dimension, shared strings and tables. Only the empty-ref merge cell panicked; everything else returned a clean error. The other parsing paths look well guarded. ### Suggested fix Skip the entry when the rectangle is empty, before the range test: if len(ws.MergeCells.Cells[i].rect) == 0 { continue } Credit goes to arpitjain099.

Source published

7 Oct 2026 20:23:17 UTC

Source modified

5 Nov 2026 23:26:10 UTC

Observed here

5 Nov 2026 23:38:32 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Publisher rating · MODERATE

Excelize: Panic in cellInRange on a worksheet with an empty mergeCell ref in github.com/xuri/excelize

Source published

5 Nov 2026 22:53:46 UTC

Source modified

5 Nov 2026 23:15:11 UTC

Observed here

5 Nov 2026 23:38:32 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.