CVE-2026-4983
MediumCVSS 4.1Exploitation Probability (EPSS)
Low risk16th percentile - higher than 16% of all known CVEs
Summary
The Open VSX Registry does not sanitize SVG files uploaded as extension icons prior to storage, allowing the publication of a malicious extension with an SVG icon. This leads to stored XSS attacks when a user navigates directly to the icon URL.
Risk Assessment
An attacker can execute scripts within the Open VSX application context, leading to session hijacking and authentication token theft. In deployments using external storage, the risk is limited to phishing attacks and credential harvesting.
Recommendation
It is recommended to implement sanitization of SVG files before storage and to add appropriate security headers such as Content-Security-Policy. Consider restricting the ability to publish extensions by unauthorized users.
Other vulnerabilities in Open VSX Registry
See all- CVE-2026-89321Medium
The VSIX publishing service limits the compressed file size (ovsx.publishing.max-content-size, 512 MB by default) but does not limit the decompressed entry size. WebResourceService opens the entry via ZipFile.getInputStream() and copies the decompressed stream without counting bytes, and the java.io.tmpdir cache is evicted by entry count (150), not size, allowing a publisher with their own namespace to fill the temp filesystem.
- CVE-2026-13323Medium
In Open VSX Registry before version 1.0.2, the /vscode/unpkg/ endpoint serves user-supplied HTML files with Content-Type: text/html and without Content-Security-Policy or Content-Disposition: attachment headers. An unauthenticated attacker can register a publisher account, upload a VSIX containing a crafted HTML payload, and trick an authenticated user into visiting the resulting URL.
Original NVD description (English source)
Open VSX Registry does not sanitize SVG files uploaded as extension icons prior to storage, and serves them with Content-Type: image/svg+xml without security headers such as Content-Security-Policy or Content-Disposition: attachment. This allows an attacker to publish an extension with a malicious SVG icon and achieve stored cross-site scripting (XSS) when a user navigates directly to the icon URL. On deployments using local storage, script execution occurs within the Open VSX application origin, enabling session hijacking, authentication token theft, and unauthorized extension publishing. On deployments backed by external storage (such as open-vsx.org with an S3-backed CDN), execution is confined to the storage origin, reducing impact but still permitting phishing attacks and credential harvesting through attacker-crafted pages.