---
id: "CVE-2025-69723"
kind: "vulnerability"
aliases: ["CVE-2025-69723"]
title: "LocalStack: reflected XSS in v4.9.2 runs script in a victim's browser"
severity: "medium"
cvss: null
epss: 0.00148
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["aws-emulation", "ci", "developers", "localstack", "package"]
not_affected_if: ["not-exposed-to-browser", "other-version"]
published_at: "2026-10-22T19:17:33+00:00"
first_seen_at: "2026-10-23T21:57:31+00:00"
updated_at: "2026-10-25T05:00:21+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-69723", "first_seen_at": "2026-10-23T21:57:31+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2025-69723", "first_seen_at": "2026-10-24T07:15:51+00:00"}]
---

# LocalStack: reflected XSS in v4.9.2 runs script in a victim's browser

LocalStack v4.9.2 reflects part of a crafted URL into a page without escaping it. A victim who opens such a link has attacker JavaScript run in their browser session.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed LocalStack version with `localstack --version` or the image tag in your compose file.
- Look for LocalStack web endpoints exposed beyond your own machine or developer network.

## Fix

- Upgrade LocalStack past `4.9.2` once a fixed release is published; the sources do not name a fixed version.
- Until then, do not expose the LocalStack port to untrusted users or browsers you do not control.

## Timeline

- 2026-10-23T21:57:31+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2025-69723
- 2026-10-24T07:15:51+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2025-69723

## From the sources

A reflected cross-site scripting (XSS) vulnerability in localstack v4.9.2 allows attackers to execute arbitrary Javascript in the context of the user's browser via a crafted URL.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_