CVE-2026-58228Scheme validation bypass in Phoenix.LiveView.Utils leads to XSS via <.link>

Official description

Cross-site scripting vulnerability in phoenixframework phoenix_live_view allows an attacker to bypass URL scheme validation and execute JavaScript in a victim's browser session. The Phoenix.LiveView.Utils.valid_destination!/2 and Phoenix.LiveView.Utils.valid_live_navigation_destination!/2 functions in lib/phoenix_live_view/utils.ex rely on an internal uri_scheme/1 helper that only detects a scheme when the input's first byte is an ASCII letter. Inputs beginning with an ASCII control character or space fall through to a nil-returning clause, causing the URL to be treated as a safe relative path. Standard browsers implement the WHATWG URL parser, which strips leading C0 control and space characters before parsing. As a result, an input such as " javascript:alert(1)" is passed unchanged into <.link href={...}> and, when clicked, is parsed by the browser as a javascript: URL that executes attacker-controlled script in the victim's session. Applications that render user-supplied URLs (for example profile links, redirect targets, or external references) via <.link href={...}> are affected. This issue affects phoenix_live_view: from 1.2.2 before 1.2.7.

Affected products (as reported)

References

• https://github.com/phoenixframework/phoenix_live_view/security/advisories/GHSA-5cgh-g58j-m9cq vendor-advisory, related
• https://cna.erlef.org/cves/CVE-2026-58228.html related
• https://osv.dev/vulnerability/EEF-CVE-2026-58228 related
• https://github.com/phoenixframework/phoenix_live_view/commit/86165533e311469a1b62093fd182d9d874de8106 patch