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Actively exploited

CVE-2023-7101 Spreadsheet::ParseExcel Remote Code Execution Vulnerability

Spreadsheet::ParseExcel contains a remote code execution vulnerability due to passing unvalidated input from a file into a string-type “eval”. Specifically, the issue stems from the evaluation of Number format strings within the Excel parsing logic.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch urgentlyCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 2 Jan 2024.
  • Rated High severity (CVSS 7.8, scored by CISA).
  • It has been in the catalogue for 1,039 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

Spreadsheet::ParseExcel version 0.65 is a Perl module used for parsing Excel files. Spreadsheet::ParseExcel is vulnerable to an arbitrary code execution (ACE) vulnerability due to passing unvalidated input from a file into a string-type “eval”. Specifically, the issue stems from the evaluation of Number format strings (not to be confused with printf-style format strings) within the Excel parsing logic.

Affected Versions

ProductVersions
Douglas Wilson Spreadsheet::ParseExcel0.65

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Spreadsheet::ParseExcel. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated high, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 23 Jan 2024 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2023-7101
  3. CVE record: CVE-2023-7101
  4. FIRST EPSS
  5. github.com/mandiant/Vulnerability-Disclosures/blob/master/2023/MNDT-2023-0019.md
  6. https://www.cve.org/CVERecord?id=CVE-2023-7101
  7. https://metacpan.org/dist/Spreadsheet-ParseExcel
  8. https://github.com/haile01/perl_spreadsheet_excel_rce_poc
  9. github.com/jmcnamara/spreadsheet-parseexcel/blob/c7298592e102a375d43150cd002feed806557c15/lib/Spread
  10. openwall.com/lists/oss-security/2023/12/29/4
  11. lists.debian.org/debian-lts-announce/2023/12/msg00025.html
  12. https://github.com/jmcnamara/spreadsheet-parseexcel/commit/bd3159277e745468e2c553417b35d5d7dc7405bc