CVE-2026-61456: XSS (CVSS 4.6)

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.

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CVSS v3.1 Score

4.6

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0014

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://github.com/getgrav/grav/security/advisories/GHSA-7vhm-8x52-2r5p https://www.vulncheck.com/advisories/grav-before-stored-xss-via-svg-upload-api https://github.com/getgrav/grav/security/advisories/GHSA-7vhm-8x52-2r5p

Frequently Asked Questions

What is CVE-2026-61456? +

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. It has a CVSS v3.1 base score of 4.6 (MEDIUM).

How severe is CVE-2026-61456? +

CVE-2026-61456 has a CVSS v3.1 score of 4.6 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0014, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-61456? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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