CVE-2026-58657
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.
References
- https://github.com/getgrav/grav/commit/6582166173bb8eb5869d96aea384e0e73777c94c
- https://github.com/getgrav/grav/commit/e03d29aa0d3ece16d73c1ffccfa78df8bf5f28b8
- https://github.com/getgrav/grav/security/advisories/GHSA-ffmg-hfvg-jhg9
- https://www.vulncheck.com/advisories/grav-stored-css-injection-via-markdown-image-resize-action
- https://github.com/getgrav/grav/security/advisories/GHSA-ffmg-hfvg-jhg9