Excelize ANCHORARRAY: mutually-referencing array formulas recurse unboundedly via re-entrant CalcCellValue, causing a fatal stack overflow

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 2.8.1 to 2.11.0, ANCHORARRAY recursively calls the exported CalcCellValue function, creating a fresh calculation context at each cycle and bypassing in-flight and iteration controls. ANCHORARRAY calls CalcCellValue instead of cellResolver, so each recursive hop receives a new calcContext and loses cycle state. When mutually referencing dynamic-array formulas are evaluated directly or through formula-evaluating APIs, each recursion hop resets the cycle budget and prevents completion-based caches from breaking the cycle, allowing an attacker to cause a fatal Go stack overflow and abort the process. No fixed version is available as of this review.

Source published

7 Oct 2026 17:51:31 UTC

Source modified

7 Oct 2026 18:51:04 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. From 2.8.1 to 2.11.0, ANCHORARRAY recursively calls the exported CalcCellValue function, creating a fresh calculation context at each cycle and bypassing in-flight and iteration controls. ANCHORARRAY calls CalcCellValue instead of cellResolver, so each recursive hop receives a new calcContext and loses cycle state. When mutually referencing dynamic-array formulas are evaluated directly or through formula-evaluating APIs, each recursion hop resets the cycle budget and prevents completion-based caches from breaking the cycle, allowing an attacker to cause a fatal Go stack overflow and abort the process. No fixed version is available as of this review.

Source published

Oct 7, 2026, 5:51:31 PM (timezone not stated)

Source modified

Oct 7, 2026, 6:51:04 PM (timezone not stated)

Observed here

7 Nov 2026 12:38:44 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 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. From 2.8.1 to 2.11.0, ANCHORARRAY recursively calls the exported CalcCellValue function, creating a fresh calculation context at each cycle and bypassing in-flight and iteration controls. ANCHORARRAY calls CalcCellValue instead of cellResolver, so each recursive hop receives a new calcContext and loses cycle state. When mutually referencing dynamic-array formulas are evaluated directly or through formula-evaluating APIs, each recursion hop resets the cycle budget and prevents completion-based caches from breaking the cycle, allowing an attacker to cause a fatal Go stack overflow and abort the process. No fixed version is available as of this review.

Source published

7 Oct 2026 18:17:19 UTC

Source modified

13 Oct 2026 14:23:43 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 3.1 · [email protected] · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

### Summary `ANCHORARRAY` (calc.go:15137 on current master) evaluates each cell of the referenced spill range by calling the **exported** `CalcCellValue`, which unconditionally constructs a fresh `calcContext` — fresh entry marker, fresh iterations map, full `MaxCalcIterations` budget (calc.go:896-900). The circular-reference control only exists **within one context**: the entry-exclusion marker and per-ref iteration budget are fields of that single context, and completion-based caching (`formulaArgCache`/`calcRawCache`) only ever stores results of evaluations that *finish*. During a pure cycle no nested evaluation ever finishes, so nothing is ever cached to break the recursion, and each hop re-arms the entire budget. Two ordinary, Excel-legal constructs in an attacker-supplied workbook are enough: - `A1` (dynamic array formula, ref `A1:A1`): `_xlfn.ANCHORARRAY($B$1)` - `B1` (dynamic array formula, ref `B1:B1`): `_xlfn.ANCHORARRAY($A$1)` → `CalcCellValue → calcCellValue → evalInfixExp → parseReference → cellResolver → … → ANCHORARRAY → CalcCellValue → …` forever, ending in a **fatal, unrecoverable** Go runtime error: `runtime: goroutine stack exceeds …-byte limit / fatal error: stack overflow`. Go stack overflows cannot be recovered — the whole process aborts. ### Details - The terminating edge the iterations gate is supposed to provide does not exist across contexts: there is no in-flight tracking shared between nested `CalcCellValue` calls. - Both formulas are ordinary Excel-legal constructs; no exotic XML is required. - Excelize's own APIs reach formula evaluation on untrusted cells implicitly (e.g. `pivotTable.go:538`, `picture.go:985/1141`, `col.go:892`), so a service that merely adds a pivot table or a picture over such a workbook dies. - No option value prevents it: `MaxCalcIterations` is irrelevant because every hop gets a fresh budget. - Measured: a 64 MB stack budget is exhausted in ~0.09 s; the ~1 GB default in ~1–2 s. ### PoC A standalone program (public API only) was provided to the maintainer by email (`4-anchorarray-recursion`): `NewFile` + `SetCellFormula` with `FormulaOpts{Type: array, Ref: A1:A1 / B1:B1}`, then `CalcCellValue("Sheet1","A1")`. On master `ecd99d761fe0` (2026-09-08) the process aborts with `fatal error: stack overflow`; with the proposed patch the cycle terminates normally (`CYCLE_TERMINATED`) and existing calc tests pass. ### Impact An attacker ships a workbook containing the two formulas; any service that evaluates a formula over those cells — directly via `CalcCellValue`, or implicitly via `AddPivotTable` / `AddPicture` / auto-fit — aborts. Remote, unauthenticated, process-fatal, no configuration prevents it. ### Proposed fix Evaluate spill-range cells through the **current** calculation context — `fn.f.cellResolver(fn.ctx, …)` instead of the exported `CalcCellValue` — so the entry check and iterations gate of the running calculation apply. `cellResolver` returns the typed value directly (dropping a string round-trip); an `ArgEmpty → ""` shim preserves the existing `ToNumber` behavior for empty spill cells, and a fresh-context fallback covers the legacy nil-ctx test paths. A complete patch has been provided to the maintainer.

Source published

8 Oct 2026 16:31:21 UTC

Source modified

19 Oct 2026 21:41:18 UTC

Observed here

24 Oct 2026 13:19:41 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:N/S:U/C:N/I:N/A:H

Publisher rating · HIGH

Mutually-referencing array formulas recurse unboundedly, causing a fatal stack overflow 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.