Security Vulnerabilities
The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. Prior to 1.7.7, the public catalogue UI served at GET / (file internal/api/handlers/v0/ui_index.html) is vulnerable to stored cross-site scripting via the server.websiteUrl field of any published server.json. Server-side validation in internal/validators/validators.go (validateWebsiteURL) only checks that the URL parses, is absolute, and uses the https scheme; it does not reject quote characters. Client-side, the value is interpolated into a double-quoted href attribute via innerHTML, using a homegrown escapeHtml helper that performs the standard textContent → innerHTML round-trip. Per the HTML serialisation algorithm, that round-trip encodes only &, <, > and U+00A0 inside text nodes — it does not encode " or '. A literal " in websiteUrl therefore breaks out of the href attribute, allowing arbitrary on* event handlers to be appended to the same <a> element. The Content-Security-Policy on / is script-src 'self' 'unsafe-inline' https://cdn.tailwindcss.com, so the injected event handlers execute. Any user able to obtain a publish token (e.g. via POST /v0/auth/github-at with their own GitHub account, or POST /v0/auth/none on a deployment that has anonymous auth enabled) can plant a poisoned record visible to every visitor of the registry homepage. This vulnerability is fixed in 1.7.7.
CVSS Score
5.1
EPSS Score
0.0
Published
2026-05-14
The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. Prior to 1.7.7, the Registry's HTTP-based namespace verification (POST /v0/auth/http, POST /v0.1/auth/http) uses safeDialContext (internal/api/handlers/v0/auth/http.go:67-110) to refuse dialling private/internal addresses when fetching the well-known public-key file from a publisher-supplied domain. The blocklist (isBlockedIP, lines 125-133) relies entirely on Go stdlib's IsLoopback / IsPrivate / IsLinkLocalUnicast / IsMulticast / IsUnspecified plus a manual CGNAT range. None of these cover IPv6 6to4 (2002::/16), NAT64 (64:ff9b::/96 and 64:ff9b:1::/48 per RFC 8215), or deprecated site-local (fec0::/10) — all of which encode arbitrary IPv4 in the address bits and tunnel to RFC1918 / cloud-metadata services on dual-stack / NAT64-enabled hosts. This vulnerability is fixed in 1.7.7.
CVSS Score
6.3
EPSS Score
0.0
Published
2026-05-14
Use after free in Extensions in Google Chrome on Mac prior to 148.0.7778.168 allowed an attacker who convinced a user to install a malicious extension to execute arbitrary code via a crafted Chrome Extension. (Chromium security severity: Medium)
CVSS Score
8.8
EPSS Score
0.0
Published
2026-05-14
Integer overflow in Fonts in Google Chrome prior to 148.0.7778.168 allowed a remote attacker to execute arbitrary code inside a sandbox via a crafted HTML page. (Chromium security severity: Medium)
CVSS Score
8.8
EPSS Score
0.001
Published
2026-05-14
Out of bounds read in GPU in Google Chrome on Linux prior to 148.0.7778.168 allowed a remote attacker who had compromised the renderer process to leak cross-origin data via a crafted HTML page. (Chromium security severity: Medium)
CVSS Score
3.1
EPSS Score
0.0
Published
2026-05-14
Insufficient validation of untrusted input in Skia in Google Chrome prior to 148.0.7778.168 allowed a remote attacker who had compromised the renderer process to perform an out of bounds memory write via a crafted print file. (Chromium security severity: Medium)
CVSS Score
3.1
EPSS Score
0.0
Published
2026-05-14
Use after free in Mojo in Google Chrome prior to 148.0.7778.168 allowed a remote attacker to potentially perform a sandbox escape via a crafted HTML page. (Chromium security severity: Medium)
CVSS Score
9.6
EPSS Score
0.001
Published
2026-05-14
Use after free in GPU in Google Chrome prior to 148.0.7778.168 allowed a remote attacker to execute arbitrary code inside a sandbox via a crafted HTML page. (Chromium security severity: Medium)
CVSS Score
8.8
EPSS Score
0.001
Published
2026-05-14
Object lifecycle issue in Dawn in Google Chrome prior to 148.0.7778.168 allowed a remote attacker to obtain potentially sensitive information from process memory via a crafted HTML page. (Chromium security severity: Medium)
CVSS Score
5.3
EPSS Score
0.0
Published
2026-05-14
Insufficient policy enforcement in WebXR in Google Chrome on Android prior to 148.0.7778.168 allowed a remote attacker who had compromised the renderer process to obtain potentially sensitive information from process memory via a crafted HTML page. (Chromium security severity: Medium)
CVSS Score
5.3
EPSS Score
0.001
Published
2026-05-14