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.
PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. Prior to 1.30.4, 2.1.16, 2.4.5, 3.10.5, and 5.7.0, 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. This vulnerability is fixed in 1.30.4, 2.1.16, 2.4.5, 3.10.5, and 5.7.0.
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
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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。
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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 github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com