# Marshmallow has DoS in Schema.load(many)

Advisory record · `GHSA-428g-f7cq-pgp5`

- **Identifiers:** `GHSA-428g-f7cq-pgp5` · `CVE-2025-68480` · `PYSEC-2026-1605`
- **State:** Confirmed
- **Severity:** CVSS 5.3 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-405](https://cwe.mitre.org/data/definitions/405.html)
- **Tags:** [CWE-405](https://agentprime.io/advisories/tag/cwe-405.md)
- **Published:** 22 Dec 2025
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 22 Dec 2025, 20:20 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `marshmallow` (PyPI): affected `>=3.0.0rc1, <3.26.2 || >=4.0.0, <4.1.2`; fixed in `3.26.2`, `4.1.2`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Marshmallow versions 3.0.0rc1 up to 3.26.2 and 4.0.0 up to 4.1.2 are affected. A moderately sized input passed to Schema.load with many=True can consume a disproportionate amount of CPU time, enabling a denial of service attack. Upgrade to marshmallow 3.26.2 or 4.1.2. The source gives few details about the attack conditions.

Written 5 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 5.3 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0030, the 22nd percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:34 UTC: First seen by agentprime
- 31 Oct 2026, 14:34 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-428g-f7cq-pgp5)

## Sources

- [GitHub Advisory Database: GHSA-428g-f7cq-pgp5](https://github.com/advisories/GHSA-428g-f7cq-pgp5)
- [OSV: GHSA-428g-f7cq-pgp5](https://osv.dev/vulnerability/GHSA-428g-f7cq-pgp5)
- <https://github.com/marshmallow-code/marshmallow/security/advisories/GHSA-428g-f7cq-pgp5>
- <https://nvd.nist.gov/vuln/detail/CVE-2025-68480>
- <https://github.com/marshmallow-code/marshmallow/commit/d24a0c9df061c4daa92f71cf85aca25b83eee508>
- <https://github.com/marshmallow-code/marshmallow>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-428g-f7cq-pgp5>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-428g-f7cq-pgp5/>. Everything for agents: <https://agentprime.io/llms.txt>.