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Phoenix Live View CVE-2026-58228

MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-07-13 EEF
5.1
CVSS 4.0 · Vendor: EEF
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Jul 13, 2026

URL scheme validation bypass in Phoenix LiveView 1.2.2–1.2.6 allows unauthenticated attackers to inject javascript: URLs that execute in a victim's browser session when clicked. The root cause is a first-byte ASCII letter guard in the internal uri_scheme/1 helper: inputs prefixed with whitespace or C0 control characters bypass scheme detection entirely and are treated as safe relative paths, while WHATWG-compliant browsers silently strip those leading bytes before parsing — converting what LiveView sees as a harmless string into an executable javascript: URL. Applications rendering user-supplied URLs (profile links, redirect targets, external references) via the <.link href={...}> component are directly affected; no public exploit code has been identified at time of analysis, and a patched release (1.2.7) is available.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (EEF) PRIMARY 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

Primary rating from Vendor (EEF) · only source for this CVE.

CVSS VectorVendor: EEF

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
Active
Vulnerable system: Confidentiality
Low
Vulnerable system: Integrity
Low
Vulnerable system: Availability
None
Subsequent system: Confidentiality
High
Subsequent system: Integrity
High
Subsequent system: Availability
None

DescriptionCVE.org

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.

Threat Intelligence Overview

EPSS Score
0.4%
Top 70% exploitable
Data Quality
6 sources
Confidence: High
NVD CVE.org EPSS Vulnrichment GitHub VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.4%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
Poc
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

Affected Products (CPE)CVE.org

cpe:2.3:a:phoenixframework:phoenix_live_view:*:*:*:*:*:*:*:*
cpe:2.3:a:phoenixframework:phoenix_live_view:*:*:*:*:*:*:*:*

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