How severe is CVE-2026-40902?

CVE-2026-40902 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-40902 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-40902?

CVE-2026-40902 affects Phpoffice Phpspreadsheet. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-40902?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-40902 have an EU (EUVD) identifier?

Yes. CVE-2026-40902 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29852.

When was CVE-2026-40902 published?

CVE-2026-40902 was published on 2026-05-12 and last updated on 2026-06-17.

CVE-2026-40902

CVE-2026-40902 is a high-severity vulnerability in Phpoffice Phpspreadsheet with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (32nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-29852
Weakness: CWE-770
Affected product: Phpoffice Phpspreadsheet
Published: 2026-05-12
Last modified: 2026-06-17

Description

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 <row r="999999999"/> 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.

Frequently asked questions

What is CVE-2026-40902?: 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 <row r="999999999"/> 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.
How severe is CVE-2026-40902?: CVE-2026-40902 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-40902 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-40902?: CVE-2026-40902 affects Phpoffice Phpspreadsheet. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-40902?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-40902 have an EU (EUVD) identifier?: Yes. CVE-2026-40902 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29852.
When was CVE-2026-40902 published?: CVE-2026-40902 was published on 2026-05-12 and last updated on 2026-06-17.

References

https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-7c6m-4442-2x6m

Affected products (1)

cpe:2.3:a:phpoffice:phpspreadsheet:*:*:*:*:*:*:*:*

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