Duplicate Advisory: Grav: Stored CSS injection via Markdown image resize() bypasses prior media style sanitizers in Grav

Overview

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-ffmg-hfvg-jhg9. This link is maintained to preserve external references.

Original Description

Grav before 2.0.0 (affected through 2.0.0-rc.9 and the 2.0 branch) contains a stored CSS injection vulnerability in the Markdown image resize() media action. Prior media hardening rejects direct ?style= payloads and unsafe attribute() fallbacks, but the resize() action in Excerpts::processMediaActions() writes caller-controlled values directly into the image's styleAttributes. A lower-privileged content editor who can edit page Markdown can store a crafted image URL with semicolon-delimited CSS declarations in the resize parameters, which are rendered into the final <img style=...> attribute when a higher-privileged reviewer/admin views the page or preview. This does not require JavaScript execution but enables UI redress/overlay and content-manipulation attacks (e.g., a full-viewport fixed overlay). Fixed in 2.0.0.

Affected packages

• getgrav/grav = 2.0.0-rc.9

Remediation

Refer to the advisory for the patched release.