Versions of the package hackney before 1.21.0 are vulnerable to Server-side Request Forgery (SSRF) due to improper parsing of URLs by URI built-in module and hackey. Given the URL http://127.0.0.1?@127.2.2.2/, the URI function will parse and see the host as 127.0.0.1 (which is correct), and hackney will refer the host as 127.2.2.2/. This vulnerability can be exploited when users rely on the URL function for host checking.

Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability? One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.