# What changed in marshmallow

> 1 change in marshmallow 4 from its official release notes, upgrade guides and advisories: 1 security. Each one cited. Sources checked 2026-10-25. HTML: https://unstale.sh/pypi/marshmallow/

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## marshmallow 4

### Security

- Marshmallow has DoS in Schema.load(many) (3.26.2, 4.1.2) — [security advisory](https://github.com/advisories/GHSA-428G-F7CQ-PGP5)