CVE-2026-55890 Grav: Stored CSS injection via Markdown image ?style=… reaches MediaObjectTrait::style()
Attackers can inject malicious CSS via Markdown image styles in Grav, potentially leading to script execution or session hijacking.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-55890?
CVE-2026-55890 is a medium-severity cross-site scripting vulnerability in getgrav grav, published on 10 Jul 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official description
Grav is a file-based Web platform. Prior to 2.0.0-rc.9, Grav's incomplete fix for stored XSS through the Markdown media attribute action (CVE-2026-42841) leaves the sibling MediaObjectTrait::style method reachable through the same Markdown excerpt-action pipeline, allowing an editor to save Markdown image style parameters that are written into the rendered img style attribute without sanitization. This issue is fixed in version 2.0.0-rc.9.
Weakness: CWE-79
Which versions are affected by CVE-2026-55890?
2 open source packages ship an affected version, including getgrav/grav.
| Package | Affected | Fixed in |
|---|---|---|
getgrav/grav Packagist | All versions | 2.0.0-rc.9 |
getgrav/grav Packagist | All versions | 2.0.0-rc.9 |
How do I fix CVE-2026-55890?
Upgrade getgrav/grav to 2.0.0-rc.9 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-55890 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55890 exists.
Sources
Also known as GHSA-pmf8-g7c8-7v54.