EUVD-2026-42905
GHSA-g78v-pr5g-35v2
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Network vector via API upload, low privilege (api.media.write account), user interaction required (admin opens SVG), scope changes as script executes in admin browser context, limited C and I impact from session theft.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
2DescriptionCVE.org
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.
AnalysisAI
Stored XSS in the Grav API plugin (getgrav/grav-plugin-api) before version 1.0.3 allows an authenticated attacker holding the api.media.write permission to upload a malicious SVG file that executes arbitrary JavaScript in an administrator's browser session. The POST /api/v1/media endpoint's HandlesMediaUploads::processUploadedFile() method validates only the file extension and never calls Security::sanitizeSVG(), so the uploaded file is stored and served verbatim with Content-Type: image/svg+xml. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the attacker to hold a Grav API account with the api.media.write permission explicitly granted - this permission controls write access to the /api/v1/media endpoint and is not a default or low-barrier condition. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 4.0 score of 5.1 (Medium) is consistent with the attack's realistic constraints. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker with api.media.write API access crafts an SVG file embedding a JavaScript payload such as a fetch() call that exfiltrates document.cookie to an attacker-controlled endpoint, then uploads it via a POST request to /api/v1/media. The attacker then sends a Grav administrator a link to the stored SVG file (e.g., in a support ticket, internal message, or by embedding it in a public Grav page via an <object> tag) and waits for the administrator to open it; upon browser rendering, the embedded script executes in the admin's origin context and transmits the session token, granting the attacker full administrative access to the Grav installation. … |
| Remediation | Upgrade grav-plugin-api to version 1.0.3 or later, which corrects the vulnerability by invoking Security::sanitizeSVG() in the processUploadedFile() method. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Same weakness CWE-79 – Cross-site Scripting (XSS)
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External POC / Exploit Code
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