CVE-2026-61456: Grav before 1.0.3 Stored XSS via SVG Upload API

Severity: medium (CVSS 4.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-10 · updated 2026-10-25
Weakness: CWE-79

Description

The Grav API plugin (getgrav/grav-plugin-api) before 1.0.3 fails to sanitize SVG files uploaded through the POST /api/v1/media endpoint. The HandlesMediaUploads::processUploadedFile() method validates only the file extension and never invokes Security::sanitizeSVG(), so an authenticated attacker with the api.media.write permission can upload an SVG containing arbitrary JavaScript. The file is stored unmodified and served with Content-Type: image/svg+xml; when an administrator opens it in a browser (directly or via <object>/<iframe>), the embedded script executes in their session context, enabling cookie theft and session hijacking.

Affected products

getgrav grav: before 1.0.3 — fixed in 1.0.3

How to fix

Upgrade to a fixed version: getgrav grav 1.0.3. Check the vendor advisory for mitigations.

References

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