GHSA-xcxh-6cv4-q8p8

GHSA-xcxh-6cv4-q8p8 · HFS user adding a "web link" in HFS is vulnerable to "target=_blank" exploit

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### Summary When adding a "web link" to the HFS virtual filesystem, the frontend opens it with `target="_blank"` but without the `rel="noopener noreferrer"` attribute. This allows the opened page to use the `window.opener` property to change the location of the original HFS tab. ### Details While most modern browsers have fixes already implemented for this `target="_blank"` exploit at the browser level, users on outdated browsers remain vulnerable. This means that if an admin of the HFS instance adds a link to an external third-party service (that they believe is safe at the time) and that service they added later becomes compromised, the malicious page could replace the original HFS tab's content with a phishing page. This does not require the admin account itself to be compromised, only that a legitimate linked site turns malicious. ### Impact Affected users (people using old browsers without the browser level fix) could be misled into entering their HFS credentials or other sensitive information into a fake site controlled by an attacker. This vulnerability is fixed in most modern browsers, but adding `rel="noopener noreferrer"` remains a best practice to protect legacy environments. ### PoC Firstly, in the HFS admin page, under the filesystem (/~/admin/#/fs) press "Add" then "web link" then set the link to take the user to to an HTML file that exploits this vulnerability, here is an example of a malicious HTML file's code: ```<html> <body> <script> window.opener.location = "https://example.org"; </script> <b>Error loading...</b> </body> </html> ``` Now, in the HFS folder you placed this web link in, open HFS and click the web link, if you aren't on a modern browser that fixed this vulnerability on the browser level, then switch back to the HFS tab that opened it, and you should be taken to "https://example.org" if you tried the code I provided, or whatever other page you tried.

CVSS 6.3 · Mittel · Korrektur verfügbar

Veröffentlicht

2025-08-12T00:13:03Z

Aktualisiert

2025-08-12T20:23:55Z

Technologie-Stack: node

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