CVE-2026-117645
Received
Received - Intake
Stored XSS in Phoenix HTML
Vulnerability report for CVE-2026-117645, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-30
Last updated on: 2026-10-30
Assigner: EEF
Description
Description
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in phoenixframework phoenix_html allows an attacker who controls attribute names to inject attributes and script into rendered HTML via Phoenix.HTML.attributes_escape/1.
attributes_escape/1 in lib/phoenix_html.ex escapes attribute values but not attribute names. key_escape/1 passes a binary key through html_escape, which neutralizes quotes and angle brackets but not whitespace, so a key such as x onmouseover ends the attribute and starts a new one. An atom key is only dasherized, so any character passes, including quotes and >. Nested data, aria and phx keys take the same paths. An application is affected when it builds attribute keys from untrusted input and renders them through HEEx <tag {@attrs}>, content_tag/3, or a direct call. Before 3.0.0 the same code lived in Phoenix.HTML.Tag.
This issue affects phoenix_html: from 1.0.0 before 3.3.5 and from 4.0.0 before 4.4.0.
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| phoenixframework | phoenix_html | 1.0.0 |
| phoenixframework | phoenix_html | 4.0.0 |
| phoenixframework | phoenix_html | 6ad3a1d7960891a468d54636054a98e11dfb5111 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-79 | The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. |
