CVE-2026-59161: Excelize Streaming GetRows Row-bound Bypass Causes Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-q5j5-6p94-4gwc",
  "modified" : "2026-09-10T15:09:09Z",
  "published" : "2026-09-10T15:09:09Z",
  "aliases" : [ "CVE-2026-59161" ],
  "summary" : "Excelize: Streaming GetRows row-bound bypass causes attacker-controlled allocation",
  "details" : "# Streaming GetRows row-bound bypass causes attacker-controlled allocation\n\n## Summary\n\nExcelize's prior row-bound fix for GHSA-h69g / CVE-2026-54063 protects the checked worksheet parser, but the streaming worksheet reader used by `Rows` and `GetRows` does not enforce the same `TotalRows` bound on the row `r` attribute. A small XLSX file can set a row number above Excelize's maximum row (`1048576`) and omit the cell coordinate. `GetRows` then appends empty rows up to the attacker-controlled row index and returns success.\n\nThis was reproduced on the current default branch commit `1213a8bd7c5ab360554603ac5c995ccaf6eb4314` and the latest release tag `v2.10.1` (`5ad5ab3af0054c55bdce09f1530085600e9f2e45`).\n\n## Affected package\n\n- Package: `github.com/xuri/excelize/v2`\n- Tested affected versions: current default branch at `1213a8bd7c5ab360554603ac5c995ccaf6eb4314`, and release `v2.10.1`\n- Fixed version: none known at the time of this report\n\n## Impact\n\nAn attacker who can provide an XLSX file to an application that calls `GetRows` can cause memory and CPU usage to scale with an attacker-controlled row number, even though the file itself is tiny. This is an availability issue and appears to be an incomplete coverage variant of the GHSA-h69g row-index allocation class.\n\nIn the conservative PoC, `row r=\"2000000\"` returned a `[][]string` with length 2,000,000 and allocated about 46 MB. Larger row numbers scale the allocation further.\n\n## Root cause\n\nThe checked parser path validates row numbers:\n\n- `excelize.go`: `checkRowNum(r int)` rejects negative rows and rows greater than `TotalRows`.\n- `excelize.go`: `checkSheet()` calls `checkRowNum(r.R)` before allocating sheet rows.\n- `workSheetReader()` invokes `checkSheet()` / `checkRow()` before returning a cached worksheet.\n\nThe streaming path does not use that checked parser:\n\n- `rows.go`: `Rows(sheet)` opens an XML decoder directly.\n- `Rows.Next()` accepts the row `r` attribute and assigns it to the iterator's current row without applying `checkRowNum()`.\n- `Rows.Columns()` also assigns row `r` to the iterator state without applying `checkRowNum()`.\n- `GetRows()` appends empty row slices for the gap between the previous row and the current row.\n\nBecause a cell without an `r` coordinate can still contain a value, the worksheet can avoid cell-coordinate row validation while still causing `GetRows()` to materialize rows up to the out-of-range row number.\n\n## Minimal worksheet payload\n\n```xml\n<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<worksheet xmlns=\"http://schemas.openxmlformats.org/spreadsheetml/2006/main\">\n  <sheetData>\n    <row r=\"2000000\"><c t=\"s\"><v>0</v></c></row>\n  </sheetData>\n</worksheet>\n```\n\nThe workbook also contains a normal `sharedStrings.xml` with one string (`ok`).\n\n## Reproduction\n\nA minimal Go harness creates the XLSX in memory and calls `GetRows(\"Sheet1\")`:\n\n```go\nrows, err := f.GetRows(\"Sheet1\")\nfmt.Println(\"rows_len:\", len(rows))\nif len(rows) > 0 {\n    fmt.Println(\"last_row:\", rows[len(rows)-1])\n}\nfmt.Printf(\"returned error: %T %v\\n\", err, err)\n```\n\nObserved output on current default branch commit `1213a8bd7c5ab360554603ac5c995ccaf6eb4314`:\n\n```text\n== streaming GetRows row r=2000000 cell without r ==\nrows_len: 2000000\nlast_row: [ok]\nreturned error: <nil> <nil>\nelapsed=21ms alloc_delta=46MB\n```\n\nObserved output on latest release tag `v2.10.1`:\n\n```text\n== streaming GetRows row r=2000000 cell without r ==\nrows_len: 2000000\nlast_row: [ok]\nreturned error: <nil> <nil>\nelapsed=14ms alloc_delta=46MB\n```\n\nA control using the checked parser with `row r=\"1048577\"` and `c r=\"A1048577\"` correctly returns `row number exceeds maximum limit`, confirming this report is about inconsistent enforcement in the streaming path rather than a missing global constant.\n\n## Expected behavior\n\n`Rows` / `GetRows` should reject row numbers greater than `TotalRows` with the same error behavior as the checked parser path.\n\n## Suggested remediation\n\n- Apply the same row-bound validation in the streaming reader immediately after parsing a row `r` attribute.\n- Preserve and return row parsing errors from `GetRows()` instead of silently continuing or returning only `Rows.Close()` errors.\n- Add regression tests for `GetRows()` on a worksheet containing `row r=\"1048577\"` with a cell value but no cell `r` coordinate.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/xuri/excelize/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.11.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/xuri/excelize"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.4.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/qax-os/excelize/security/advisories/GHSA-q5j5-6p94-4gwc"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-59161"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/qax-os/excelize/pull/2331"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/qax-os/excelize/commit/93f0b3caed37f21ef5079e3259c6c21dcfe68453"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/qax-os/excelize"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/qax-os/excelize/releases/tag/v2.11.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400", "CWE-770" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-10T15:09:09Z",
    "nvd_published_at" : "2026-07-10T17:17:02Z"
  }
}