Vulnerability in github.com/modelcontextprotocol/registry (CVE-2026-44429)
Summary
Vulnerability in github.com/modelcontextprotocol/registry (CVE-2026-44429). Risk of unauthorized operations or information disclosure. Exploitable via POST /v0/auth/github-at. Mitigation: upgrade to 1.7.7 or later.
Original description
The description as published by the source.
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 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.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-44429 has been found in github.com/modelcontextprotocol/registry.
Attackers can target a specific entry point like POST /v0/auth/github-at over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.4/10.
What to do: upgrade github.com/modelcontextprotocol/registry to 1.7.7 or later.
If unsure, ask your IT team or search "github.com/modelcontextprotocol/registry CVE-2026-44429" on the vendor's site.
CVE-2026-44429 (github.com/modelcontextprotocol/registry) — CWE-116 / CVSS v3 5.4
Attack vector: remote (network-reachable)
Attack surface: POST /v0/auth/github-at / POST /v0/auth/none / server.websiteUrl / validateWebsiteURL
Patched: 1.7.7 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-116) exists in github.com/modelcontextprotocol/registry. Attackers reach the vulnerable code path via POST /v0/auth/github-at.
Check the vendor advisory for the affected versions of github.com/modelcontextprotocol/registry. Attack surface: POST /v0/auth/github-at / POST /v0/auth/none / server.websiteUrl / validateWebsiteURL.
Severity: Medium (CVSS 5.4/10). Risk of unauthorized operations or information disclosure.
Update to 1.7.7.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /v0/auth/github-at requests with malformed payloads or SQL meta-characters. Run grep -r 'github.com/modelcontextprotocol/registry' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'github.com/modelcontextprotocol/registry' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/modelcontextprotocol/registryを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'POST /v0/auth/github-at' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /v0/auth/github-atへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply patch patch
Upgrade github.com/modelcontextprotocol/registry to 1.7.7ステージング環境で 1.7.7 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。
-
4Post-deployment verification verify
Replay attack against POST /v0/auth/github-at on staging to confirm patch closes the vectorパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com