Weakness Type (CWE)

CWE-79 — CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CAPEC

CVSS 4.0 Score

5.1

MEDIUM

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:L/VI:L/VA:N/SC:H/SI:H/SA:N

Vulnerability 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

pkg:hex/phoenix_live_view

Module Source File Routine
Phoenix.LiveView.Utils lib/phoenix_live_view/utils.ex Phoenix.LiveView.Utils.valid_destination!/2
Phoenix.LiveView.Utils.valid_live_navigation_destination!/2
Status Type Version Changes / Fixed in
affected semver ⓘ 1.2.2 < 1.2.7

pkg:github/phoenixframework/phoenix_live_view

Module Source File Routine
Phoenix.LiveView.Utils lib/phoenix_live_view/utils.ex Phoenix.LiveView.Utils.valid_destination!/2
Phoenix.LiveView.Utils.valid_live_navigation_destination!/2
Status Type Version Changes / Fixed in
affected git ⓘ 4b63216ae6 < 86165533e3

Workarounds

Strip leading ASCII control and space bytes (code points 0x00 through 0x20) from any untrusted URL before passing it to <.link href={...}>, or reject such inputs outright. This aligns application-level validation with the WHATWG URL parser used by browsers and prevents the scheme-detection bypass.

References

Credits

  • Finder: Barna Kovacs
  • Remediation developer: Steffen Deusch
  • Analyst: José Valim
  • Analyst: Jonatan Männchen / EEF

CVE record as JSON:  GET /cves/CVE-2026-58228.json
OSV record as JSON:  GET /osv/EEF-CVE-2026-58228.json