CVE-2025-31672: Improper Input Validation vulnerability in Apache POI.

Improper Input Validation vulnerability in Apache POI.

Improper Input Validation vulnerability in Apache POI. The issue affects the parsing of OOXML format files like xlsx, docx and pptx. These file formats are basically zip files and it is possible for malicious users to add zip entries with duplicate names (including the path) in the zip. In this case, products reading the affected file could read different data because 1 of the zip entries with the duplicate name is selected over another but different products may choose a different zip entry. This issue affects Apache POI poi-ooxml before 5.4.0. poi-ooxml 5.4.0 has a check that throws an exception if zip entries with duplicate file names are found in the input file. Users are recommended to upgrade to version poi-ooxml 5.4.0, which fixes the issue. Please read https://poi.apache.org/security.html for recommendations about how to use the POI libraries securely.

Description from the National Vulnerability Database, published by security@apache.org

What it means for a small business

Apache POI runs on web servers, so this is mostly your hosting company's to fix. On shared hosting you can't patch it yourself, but you can ask.

Ask your host whether your server runs it, whether it's updated, and on what date. A good host answers that in a day.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 1.4%, higher than 71% of CVEs. That’s above average: worth scheduling this week. Scored October 31, 2026, updated daily.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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