# Medplum: Improper Validation of Redirect URI in External Auth Callback allows Authorization Code Leakage

Advisory record · `GHSA-m44r-7c5h-m6mj`

- **Identifiers:** `GHSA-m44r-7c5h-m6mj` · `CVE-2026-53728`
- **State:** Confirmed
- **Severity:** CVSS 7.1 High
- **Critical:** No
- **Weakness (CWE):** [CWE-345](https://cwe.mitre.org/data/definitions/345.html) · [CWE-601](https://cwe.mitre.org/data/definitions/601.html)
- **Tags:** [Open redirect](https://agentprime.io/advisories/tag/open-redirect.md) · [CWE-345](https://agentprime.io/advisories/tag/cwe-345.md)
- **Published:** 17 Aug 2026
- **Updated:** 17 Aug 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 17 Aug 2026, 13:36 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `@medplum/core` (npm): affected `<5.1.6`; fixed in `5.1.6`

## 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

- 7.1 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0020, the 9th percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the GitHub Advisory Database, published 17 Aug 2026. New records show when each source confirmed them.

## Sources

- [GitHub Advisory Database: GHSA-m44r-7c5h-m6mj](https://github.com/advisories/GHSA-m44r-7c5h-m6mj)
- [OSV: GHSA-m44r-7c5h-m6mj](https://osv.dev/vulnerability/GHSA-m44r-7c5h-m6mj)
- <https://github.com/medplum/medplum/security/advisories/GHSA-m44r-7c5h-m6mj>
- <https://github.com/medplum/medplum/pull/8749>
- <https://github.com/medplum/medplum/commit/7ae10035ddadde4dba7b18d3156553940465b3a1>
- <https://github.com/medplum/medplum>
- <https://github.com/medplum/medplum/releases/tag/v5.1.6>

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-m44r-7c5h-m6mj>, 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-m44r-7c5h-m6mj/>. Everything for agents: <https://agentprime.io/llms.txt>.