CVE-2026-59933

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.7%, top 51% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. In versions 4.0.0 through 5.8.0, 3.3.0 through 3.10.6, 2.2.0 through 2.4.6, 2.0.0 through 2.1.17, and all releases up to and including 1.30.5, the OLE reader follows sector chains from attacker-controlled XLS/OLE metadata without detecting cycles or enforcing a maximum chain length. A tiny malformed .xls/OLE file can set the small-block depot sector chain to point back to itself. During normal XLS detection, OLERead::read() appends the same sector data repeatedly until the PHP process exhausts memory. This is reachable from Reader\Xls::canRead() and therefore from automatic spreadsheet type detection. Applications that accept attacker-controlled spreadsheet uploads can suffer denial of service from a very small file. This issue has been fixed in versions 5.8.1, 3.10.7, 2.4.7, 2.1.18 and 1.30.6.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
65(Attend)
EG Risk 65/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
49%
KEV
Not listed

Published

July 23, 2026

Last Modified

July 30, 2026

Advisory Details (7)

Auto-updated Jul 28, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit, github_release.
github_release Patch Available

5.8.1

Patch available: PHPOffice/PhpSpreadsheet 5.8.1

https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/5.8.1
github_release Patch Available

3.10.7

Patch available: PHPOffice/PhpSpreadsheet 3.10.7

https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/3.10.7
github_release Patch Available

2.4.7

Patch available: PHPOffice/PhpSpreadsheet 2.4.7

https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/2.4.7
github_release Patch Available

2.1.18

Patch available: PHPOffice/PhpSpreadsheet 2.1.18

https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/2.1.18
github_release Patch Available

1.30.6

Patch available: PHPOffice/PhpSpreadsheet 1.30.6

https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/1.30.6
github_commit Patch Available

commit 85f2556b0bf5 (PHPOffice/PhpSpreadsheet)

Patch available: PHPOffice/PhpSpreadsheet 5.8.1 (contains commit 85f2556b0bf5)

https://github.com/PHPOffice/PhpSpreadsheet/commit/85f2556b0bf5269061bf45932ecda8a128d81750
github Patch Available🟡 PoC Available

XLS/OLE sector-chain self-loop causes memory exhaustion · Advisory · PHPOffice/PhpSpreadsheet · GitHub

https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-xh5m-36r6-47m3

Vendor Advisories for CVE-2026-59933(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFixed inDependents
phpoffice/phpspreadsheet4.0.0 ... 5.8.0 (16 versions)5.8.1—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 9× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-30 19:47 UTCEG score recompute
  2. 2026-07-30 16:28 UTCEPSS rescore
  3. 2026-07-30 10:47 UTCEG score recompute
  4. 2026-07-30 01:30 UTCEPSS rescore
  5. 2026-07-30 01:30 UTCEPSS rescore
  6. 2026-07-28 19:27 UTCEG score recompute
  7. 2026-07-28 18:24 UTCEG score recompute
  8. 2026-07-26 22:51 UTCEG score recompute
  9. 2026-07-23 15:12 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-59933?
CVE-2026-59933 is a high vulnerability published on July 23, 2026. PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. In versions 4.0.0 through 5.8.0, 3.3.0 through 3.10.6, 2.2.0 through 2.4.6, 2.0.0 through 2.1.17, and all releases up to and including 1.30.5, the OLE reader follows sector chains from attacker-controlled XLS/OLE…
When was CVE-2026-59933 disclosed?
CVE-2026-59933 was first published in the National Vulnerability Database on July 23, 2026, with the most recent update on July 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-59933 actively exploited?
CVE-2026-59933 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 50.8% of all scored CVEs.
What is the CVSS score of CVE-2026-59933?
CVE-2026-59933 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-59933?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59933, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-59933

Explore →

Is Your Infrastructure Affected by CVE-2026-59933?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs