Negative shared-string index causes panic in GetCellValue and GetRows

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/xuri/excelize/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.11.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/xuri/excelize"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "1.4.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-59162"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248",
      "CWE-755"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-10T15:08:53Z",
    "nvd_published_at": "2026-07-10T17:17:02Z",
    "severity": "MODERATE"
  },
  "details": "# Negative shared-string index causes panic in GetCellValue and GetRows\n\n## Summary\n\nExcelize parses shared-string cell values with `strconv.Atoi` and checks only the upper bound before indexing the shared string slice. If an XLSX file contains a shared-string cell with `\u003cv\u003e-1\u003c/v\u003e`, the parsed index is negative. The upper-bound check still passes (`len(sharedStrings) \u003e -1`), and Excelize indexes `sharedStrings[-1]`, causing a runtime panic.\n\nThis was reproduced on the current default branch commit `1213a8bd7c5ab360554603ac5c995ccaf6eb4314` and the latest release tag `v2.10.1` (`5ad5ab3af0054c55bdce09f1530085600e9f2e45`). The issue is independent from the row-bound allocation report, so I am reporting it separately.\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 using Excelize can trigger a process panic when the application reads the malicious cell through common APIs such as `GetCellValue` or `GetRows`. In services that parse untrusted spreadsheets without a panic recovery boundary, this can cause denial of service.\n\n## Root cause\n\nFor shared-string cells (`t=\"s\"`), `xlsxC.getValueFrom()` parses the cell value as a shared-string index and only checks whether the index is below `len(d.SI)` before indexing:\n\n```go\nxlsxSI, _ := strconv.Atoi(strings.TrimSpace(c.V))\nif len(d.SI) \u003e xlsxSI {\n    return d.SI[xlsxSI].String(), nil\n}\n```\n\nFor `xlsxSI == -1`, `len(d.SI) \u003e -1` is true, so the code proceeds to index `d.SI[-1]` and panics.\n\n## Minimal worksheet payload\n\n```xml\n\u003c?xml version=\"1.0\" encoding=\"UTF-8\"?\u003e\n\u003cworksheet xmlns=\"http://schemas.openxmlformats.org/spreadsheetml/2006/main\"\u003e\n  \u003csheetData\u003e\n    \u003crow r=\"1\"\u003e\u003cc r=\"A1\" t=\"s\"\u003e\u003cv\u003e-1\u003c/v\u003e\u003c/c\u003e\u003c/row\u003e\n  \u003c/sheetData\u003e\n\u003c/worksheet\u003e\n```\n\nThe workbook also contains a normal `sharedStrings.xml` with one string (`ok`), so the failure is specifically due to accepting a negative index.\n\n## Reproduction\n\nCalling `GetCellValue(\"Sheet1\", \"A1\")` on the workbook panics:\n\n```text\n== negative shared string GetCellValue ==\nelapsed=0s alloc_delta=0MB\nPANIC: runtime.boundsError runtime error: index out of range [-1]\n```\n\nCalling `GetRows(\"Sheet1\")` on the same workbook also panics:\n\n```text\n== negative shared string GetRows ==\nelapsed=0s alloc_delta=0MB\nPANIC: runtime.boundsError runtime error: index out of range [-1]\n```\n\nThe same results were observed on current default branch commit `1213a8bd7c5ab360554603ac5c995ccaf6eb4314` and on release `v2.10.1`.\n\n## Expected behavior\n\nMalformed shared-string indices should be rejected or treated as missing/invalid string references without panicking.\n\n## Suggested remediation\n\nCheck both lower and upper bounds before indexing the shared string table. For example:\n\n```go\nif xlsxSI \u003e= 0 \u0026\u0026 xlsxSI \u003c len(d.SI) {\n    return d.SI[xlsxSI].String(), nil\n}\n```\n\nAdd regression tests for `GetCellValue()` and `GetRows()` on `t=\"s\"` cells whose `\u003cv\u003e` value is negative.",
  "id": "GHSA-fx5j-qcqg-grpf",
  "modified": "2026-09-10T15:08:53Z",
  "published": "2026-09-10T15:08:53Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/qax-os/excelize/security/advisories/GHSA-fx5j-qcqg-grpf"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59162"
    },
    {
      "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Excelize: Negative shared-string index causes panic in GetCellValue and GetRows"
}