Vulnerability in phpoffice/phpspreadsheet (CVE-2026-40902)
Summary
Vulnerability in phpoffice/phpspreadsheet (CVE-2026-40902). Risk of unauthorized operations or information disclosure. Exploitable via cachedHighestRow. Mitigation: upgrade to 1.30.4 or later.
Original description
The description as published by the source.
Summary
The XLSX reader's ColumnAndRowAttributes::readRowAttributes() method reads row numbers from XML attributes without validating them against the spreadsheet maximum row limit (AddressRange::MAX_ROW = 1,048,576). An attacker can craft a minimal XLSX file (~1.6KB) containing a `` element that inflates cachedHighestRow to 999,999,999, causing any subsequent row iteration to attempt ~1 billion loop cycles and exhaust CPU resources.
Details
In src/PhpSpreadsheet/Reader/Xlsx/ColumnAndRowAttributes.php at line 216, the row index is cast directly from XML without bounds checking:
// ColumnAndRowAttributes.php:216
$rowIndex = (int) $row['r']; // No validation against AddressRange::MAX_ROW
This value flows through setRowAttributes() (line 126) → $this->worksheet->getRowDimension($rowNumber) (line 60), which updates the cached highest row in Worksheet.php:1348:
// Worksheet.php:1342-1349
public function getRowDimension(int $row): RowDimension
{
if (!isset($this->rowDimensions[$row])) {
$this->rowDimensions[$row] = new RowDimension($row);
$this->cachedHighestRow = max($this->cachedHighestRow, $row);
}
return $this->rowDimensions[$row];
}
The inflated cachedHighestRow is then returned by getHighestRow() (line 1099) and used as the default end bound in RowIterator::resetEnd() (RowIterator.php:86):
// RowIterator.php:86
$this->endRow = $endRow ?: $this->subject->getHighestRow();
Notably, c…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-40902 has been found in phpoffice/phpspreadsheet.
Attackers can target a specific entry point like cachedHighestRow over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade phpoffice/phpspreadsheet to 1.30.4 or later.
If unsure, ask your IT team or search "phpoffice/phpspreadsheet CVE-2026-40902" on the vendor's site.
CVE-2026-40902 (phpoffice/phpspreadsheet) — CWE-400 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: cachedHighestRow / MAX_ROW / AddressRange
Patched: 1.30.4 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-400) exists in phpoffice/phpspreadsheet. Attackers reach the vulnerable code path via cachedHighestRow without authentication.
Check the vendor advisory for the affected versions of phpoffice/phpspreadsheet. Attack surface: cachedHighestRow / MAX_ROW / AddressRange.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 1.30.4.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'phpoffice/phpspreadsheet' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'phpoffice/phpspreadsheet' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
phpoffice/phpspreadsheetを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade phpoffice/phpspreadsheet to 1.30.4ステージング環境で 1.30.4 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com