Eclipse Open Vsx

Open VSX CORS flaw leaks user tokens
CVE-2026-90882 8.7 - High - September 22, 2026

The open-vsx.org deployment returned Access-Control-Allow-Origin reflecting the requesting origin together with Access-Control-Allow-Credentials: true on the authenticated /user/ endpoints. A page on any origin could therefore issue credentialed requests to the service in a logged-in user's browser and read the responses. This exposed /user (login name, avatar, homepage, tokens URL), /user/tokens, /user/namespaces, /user/extensions, /user/search/{name} and /user/namespace/{name}/members, and because /user/csrf was readable the same way allowed the CSRF protection on write endpoints to be defeated. Chaining the two, an attacker page could call /user/token/create and exfiltrate a personal access token carrying publish and delete rights over the victim's namespaces. The headers were emitted by the CDN/edge layer, not by the application: the Open VSX software sets allowCredentials(true) in exactly one place, against a single exact origin derived from ovsx.webui.url, and defines no CORS mapping on /user/ beyond it. No configuration of the software produces origin reflection with credentials.

Permissive Cross-domain Policy with Untrusted Domains

OpenVSX Cache Poison via UrlUtil.getBaseUrl Header Injection (0.6.0+)
CVE-2025-12999 9.1 - Critical - September 21, 2026

UrlUtil.getBaseUrl builds the absolute URLs in a response download links, icons, asset and API URLs from the X-Forwarded-Host, X-Forwarded-Proto and X-Forwarded-Prefix request headers, with no check on whether the sender was a trusted proxy, falling back to the client-supplied Host header. Those responses are cached under keys that do not include the host (extension.json since 0.6.0, namespace.details.json since 0.9.0, sitemap since 0.14.5, latest.extension.version.vscode since 0.34.2). A single request carrying a forged header therefore places attacker-chosen URLs into an entry served to every other client for the lifetime of that entry one hour by default, and cluster-wide where ovsx.redis.enabled is set. The VSIX download URL, its signature URL and the public key URL are all derived from the same base URL, so extension signing does not limit the impact: an attacker who poisons an entry supplies the package, the signature over it, and the key used to verify it. Exploitability depends on deployment topology. A server reachable directly by clients, or fronted by a proxy that relays the client's X-Forwarded-Host rather than overwriting it, is exploitable by an unauthenticated remote attacker. A proxy that overwrites the header is not. An unauthenticated attacker can poison Open VSX's per-extension metadata cache with attacker-controlled download, signature, and public-key URLs by supplying a crafted X-Forwarded-Host header, causing downstream VS Code-compatible editors to fetch and install a malicious VSIX. Workarounds (unpatched versions) 1. Configure the reverse proxy to set rather than relay X-Forwarded-Host, X-Forwarded-Proto and X-Forwarded-Prefix note that nginx's $host is the client's Host header and is not a safe value. 2. Ensure the server is not reachable except through that proxy. 3. Flush the caches afterwards; poisoned entries survive the configuration change.

Insufficient Verification of Data Authenticity

Denial of Service via Unbounded Decompression in VSIX Marketplace Service
CVE-2026-89321 4.3 - Medium - September 14, 2026

Publishing limits the compressed size of a VSIX (ovsx.publishing.max-content-size, 512 MB by default) but nothing limited how large an entry becomes when opened. On the first request to /vscode/unpkg/{namespace}/{extension}/{version}/{path}, WebResourceService opened the entry with ZipFile.getInputStream() and passed the decompressed stream to Files.copy(), which ran to the end of the stream without counting bytes written. The result was cached under java.io.tmpdir, and that cache evicted by entry count (150), not by size, so it placed no bound on disk usage. A publisher with access only to their own namespace could therefore upload a small, highly compressible VSIX and cause the server to write far larger files to the temp filesystem repeating with different files or versions, since a repeat request is served from the cache. Impact observed: the temp filesystem filled; requests for files not already cached returned 500 with No space left on device; a failed extraction left a partial cache file that blocked later attempts at that path; publishing failed with Failed to read extension file. Metadata and already-cached files kept working, and the server did not stop. Triggering the extraction needs no authentication only the upload does.

Data Amplification

Open VSX Registry <1.0.2 XSS/CSRF via /vscode/unpkg/ no CSP
CVE-2026-13323 4.1 - Medium - July 01, 2026

In Open VSX Registry before 1.0.2, the /vscode/unpkg/ endpoint serves user-supplied HTML files with Content-Type: text/html and without a Content-Security-Policy or Content-Disposition: attachment response header. An unauthenticated attacker can register a publisher account, upload a VSIX containing a crafted HTML payload, and induce an authenticated user to visit the resulting URL. The browser renders the file inline in the open-vsx.org origin context, enabling session token exfiltration, persistent Personal Access Token (PAT) generation, and unauthorized publication of malicious extension versions. Because Open VSX extensions are distributed to VS Code, VSCodium, Cursor, Windsurf, and compatible editors, a compromised extension update constitutes a supply chain attack against all downstream users.

XSS

Open VSX Registry SVG XSS via Unrestricted Extension Icon Upload
CVE-2026-4983 4.1 - Medium - June 23, 2026

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.

XSS

Eclipse Open VSX: Unauthorized Extension Uploads via Unisolated Build Scripts
CVE-2025-6705 5.3 - Medium - June 27, 2025

A vulnerability in the Eclipse Open VSX Registrys automated publishing system could have allowed unauthorized uploads of extensions. Specifically, the systems build scripts were executed without proper isolation, potentially exposing a privileged token. This token enabled the publishing of new extension versions under any namespace, including those not controlled by an attacker. However, it did not permit deletion of existing extensions, overwriting of published versions, or access to administrative features of the registry. The issue was reported on May 4, 2025, fully resolved by June 24, and followed by a comprehensive audit. No evidence of compromise was found, though 81 extensions were proactively deactivated as a precaution. The standard publishing process remained unaffected. Recommendations have been issued to mitigate similar risks in the future.

Improper Control of Dynamically-Managed Code Resources

OpenVSX 0.9.00.20.0: namespace API leaks privilege escalation
CVE-2025-1007 5.3 - Medium - February 19, 2025

In OpenVSX version v0.9.0 to v0.20.0, the /user/namespace/{namespace}/details API allows a user to edit all namespace details, even if the user is not a namespace Owner or Contributor. The details include: name, description, website, support link and social media links. The same issues existed in /user/namespace/{namespace}/details/logo and allowed a user to change the logo.