Excelize: Nil-pointer dereference in GetSlicers when a worksheet has extLst present but no drawing element

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 2.9.0 to 2.11.0, GetSlicers checks for ExtLst but dereferences ws.Drawing without checking whether the independently optional drawing element exists. File.GetSlicers reads ws.Drawing.RID after seeing a worksheet extLst element even when the independently optional worksheet drawing element is absent. When a crafted worksheet contains an extLst element without a drawing element and the application calls GetSlicers, the nil ws.Drawing pointer is dereferenced while resolving the drawing relationship, allowing an attacker to panic and terminate an unprotected process. No fixed version is available as of this review.

Source published

7 Oct 2026 17:40:29 UTC

Source modified

7 Oct 2026 22:05:46 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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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: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. From 2.9.0 to 2.11.0, GetSlicers checks for ExtLst but dereferences ws.Drawing without checking whether the independently optional drawing element exists. File.GetSlicers reads ws.Drawing.RID after seeing a worksheet extLst element even when the independently optional worksheet drawing element is absent. When a crafted worksheet contains an extLst element without a drawing element and the application calls GetSlicers, the nil ws.Drawing pointer is dereferenced while resolving the drawing relationship, allowing an attacker to panic and terminate an unprotected process. No fixed version is available as of this review.

Source published

Oct 7, 2026, 5:40:29 PM (timezone not stated)

Source modified

Oct 7, 2026, 10:05:46 PM (timezone not stated)

Observed here

7 Nov 2026 12:38:36 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 4.0 · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. From 2.9.0 to 2.11.0, GetSlicers checks for ExtLst but dereferences ws.Drawing without checking whether the independently optional drawing element exists. File.GetSlicers reads ws.Drawing.RID after seeing a worksheet extLst element even when the independently optional worksheet drawing element is absent. When a crafted worksheet contains an extLst element without a drawing element and the application calls GetSlicers, the nil ws.Drawing pointer is dereferenced while resolving the drawing relationship, allowing an attacker to panic and terminate an unprotected process. No fixed version is available as of this review.

Source published

7 Oct 2026 18:17:18 UTC

Source modified

13 Oct 2026 14:24:17 UTC

Observed here

25 Oct 2026 04:17:41 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Primary · 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

### Summary GetSlicers guards only `if ws.ExtLst == nil { return }` (slicer.go:816-818) and then immediately dereferences `ws.Drawing.RID` with no nil check on ws.Drawing itself. `Drawing` and `ExtLst` are two independently optional child elements of <worksheet> in xl/worksheets/sheetN.xml, populated separately by encoding/xml depending on whether each tag is present. I executed a PoC: took a plain NewFile() workbook (no drawing, no slicer), saved it, then injected a bare `<extLst></extLst>` immediately before `</worksheet>` in xl/worksheets/sheet1.xml (no other change, no drawing element present) and called GetSlicers. Result: `runtime error: invalid memory address or nil pointer dereference`, confirmed at the ws.Drawing.RID line via stack trace. ### Reachability / who can trigger this Unauthenticated: any application that opens an untrusted .xlsx and calls the public `File.GetSlicers(sheet)` API. The trigger is a single empty XML tag with no valid slicer or drawing content required at all, making it an even smaller/simpler payload than candidate 1. ### Proof of Concept / Reproduction **Method:** 1) Reused the existing clone at C:\Users\vatsa\AppData\Local\Temp\claude\D--\59901fa2-b549-40e1-a433-30c8a3d01718\scratchpad\CVE-Hunt-10k\repos\qax-os__excelize (origin=https://github.com/qax-os/excelize.git, branch master up to date, commit e81f05008b33232151a58f06474fad5f70c4d060 dated 2026-09-27, `git describe`=v2.11.0-42-ge81f050, i.e. 42 commits past the v2.11.0 tag). 2) Manually re-read the cited source myself (not trusting the claim): slicer.go:805-820 (GetSlicers) and xmlWorksheet.go:21-72 (xlsxWorksheet struct + xlsxDrawing struct) -- confirmed verbatim, matches claim exactly. 3) Confirmed local toolchain: go version go1.27.0 windows/amd64 (/c/Program Files/Go/bin/go). 4) Built the whole package with `go build ./...` from the repo root -- succeeded with zero errors, proving the current checkout compiles cleanly. 5) Ran the pre-existing PoC test file already present in this checkout (slicer_extlst_poc_test.go, TestGetSlicersNilDrawingPanic) via `go test -run TestGetSlicersNilDrawingPanic -v .`: it builds a benign excelize.NewFile() workbook, saves it, reopens it, loads the raw zip entry xl/worksheets/sheet1.xml, string-replaces `</worksheet>` with `<extLst></extLst></worksheet>` (adds nothing else, no <drawing> anywhere), rebuilds the zip byte-for-byte otherwise unchanged (rezipReplacing helper, plain archive/zip re-encode), reopens the crafted file with excelize.OpenReader, and calls the public GetSlicers("Sheet1") API inside a recover(). 6) For a fully independent, non-test-harness reproduction, I additionally wrote and built my own separate standalone Go module+program from scratch (excelize-nilptr-repro/{go.mod,main.go} in my scratchpad dir) that imports the real, unmodified excelize package as an external library dependency via a `replace github.com/xuri/excelize/v2 => ../CVE-Hunt-10k/repos/qax-os__excelize` directive (no copy-pasted/reimplemented function -- the actual library code, used through its real public API from a separate consumer program, simulating "any application that opens an untrusted .xlsx"). This program performs the identical craft-and-open sequence but calls GetSlicers with NO recover() at all. Built with `go build -o repro.exe .` (succeeded) and ran `./repro.exe` directly, observing an unhandled process crash. **Evidence:** SOURCE VERIFICATION (current HEAD, read directly): slicer.go:816-820 is exactly as claimed -- `if ws.ExtLst == nil { return slicers, err }` followed immediately by `target := f.getSheetRelationshipsTargetByID(sheet, ws.Drawing.RID)` with no nil check on ws.Drawing. xmlWorksheet.go:54 `Drawing *xlsxDrawing `xml:"drawing"`` and xmlWorksheet.go:64 `ExtLst *xlsxExtLst `xml:"extLst"`` are both independently-optional pointer fields on xlsxWorksheet, populated only when their respective XML tag is present in the worksheet part -- confirming Drawing and ExtLst are unrelated/independent. getSheetRelationshipsTargetByID(sheet, rID string) string (sheet.go:721) takes a plain string, so `ws.Drawing.RID` is evaluated (dereferencing the nil pointer) at the call site itself. RUN 1 -- existing repo test, `go test -run TestGetSlicersNilDrawingPanic -v .`: === RUN TestGetSlicersNilDrawingPanic slicer_extlst_poc_test.go:38: original sheet1.xml: ...<sheetData>...</sheetData></worksheet> (no drawing, no extLst) slicer_extlst_poc_test.go:48: tampered sheet1.xml: ...</sheetData><extLst></extLst></worksheet> slicer_extlst_poc_test.go:59: CONFIRMED: GetSlicers panicked on nil ws.Drawing dereference: runtime error: invalid memory address or nil pointer dereference --- PASS: TestGetSlicersNilDrawingPanic (0.01s) PASS ok github.com/xuri/excelize/v2 0.100s RUN 2 -- my own independent standalone consumer program (real unmodified library via go.mod replace, NO recover installed), `./repro.exe`: [*] Saved benign workbook: 6052 bytes [*] Original sheet1.xml: ...<sheetData>...</sheetData></worksheet> [*] Tampered sheet1.xml (attacker payload -- bare empty <extLst>, still no <drawing>): ...<extLst></extLst></worksheet> [*] Crafted malicious .xlsx: 6059 bytes [*] Crafted workbook accepted by OpenReader. Calling the public GetSlicers("Sheet1") API now, no recover() installed... panic: runtime error: invalid memory address or nil pointer dereference [signal 0xc0000005 code=0x0 addr=0x20 pc=0x7ff7fc8456b8] goroutine 1 [running]: github.com/xuri/excelize/v2.(*File).GetSlicers(0x27fa8874908, {0x7ff7fc8a5e8a, 0x6}) C:/.../qax-os__excelize/slicer.go:820 +0x98 main.main() C:/.../excelize-nilptr-repro/main.go:122 +0x67f EXIT CODE: 2 The stack trace pinpoints slicer.go:820 exactly (the ws.Drawing.RID dereference), from an ordinary external caller with no recover(), on a workbook whose only "malicious" content is one empty `<extLst></extLst>` tag and zero drawing/slicer content -- confirming the claim end-to-end: nil-pointer dereference, unrecovered panic, DoS, matching CWE-476.

Source published

8 Oct 2026 16:50:08 UTC

Source modified

19 Oct 2026 21:41:00 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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 · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Publisher rating · HIGH

Nil-pointer dereference in GetSlicers when a worksheet has extLst present but no drawing element in github.com/xuri/excelize

Source published

19 Oct 2026 21:08:21 UTC

Source modified

19 Oct 2026 21:31:49 UTC

Observed here

24 Oct 2026 13:19:41 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.