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CVE-2026-34237
medium
CVSS 6.1
Vulnerability in io.modelcontextprotocol.sdk:mcp-core (CVE-2026-34237)
Summary
vulnerability in io.modelcontextprotocol.sdk:mcp-core (CVE-2026-34237). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to `0.18.3` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-34237** has been found in io.modelcontextprotocol.sdk:mcp-core.
Risk of unauthorized operations or information disclosure. CVSS score: 6.1/10.
What to do: upgrade io.modelcontextprotocol.sdk:mcp-core to **0.18.3** or later.
If unsure, ask your IT team or search "io.modelcontextprotocol.sdk:mcp-core CVE-2026-34237" on the vendor's site.
CVE-2026-34237 (io.modelcontextprotocol.sdk:mcp-core) — CWE-942 / CVSS v3 6.1
Attack vector: remote (network-reachable) / unauthenticated
Patched: `0.18.3` — 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.
❓ What is the problem
**A vulnerability** (CWE-942) exists in io.modelcontextprotocol.sdk:mcp-core.
📍 Affected scope
io.modelcontextprotocol.sdk:mcp-core — .
🔥 Severity
Severity: Medium (CVSS 6.1/10). Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **0.18.3**.
🛡️ Workaround
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'io.modelcontextprotocol.sdk:mcp-core' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'io.modelcontextprotocol.sdk:mcp-core' . | 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 `io.modelcontextprotocol.sdk:mcp-core` を grep し、稼働しているサービス・バージョンを把握する。
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6Apply patch patch
Upgrade io.modelcontextprotocol.sdk:mcp-core to 0.18.3ステージング環境で 0.18.3 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 3 で見つけた異常検知の続報チェックを含めること。
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7Post-deployment verification verify
Confirm patched version is live in production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 3 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
maven
io.modelcontextprotocol.sdk:mcp-core
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.18.3"}]}]
References
- advisory https://nvd.nist.gov/vuln/detail/CVE-2026-34237
- package https://github.com/modelcontextprotocol/java-sdk
- web https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-hv2w-8mjj-jw22
- web https://cheatsheetseries.owasp.org/cheatsheets/HTTP_Headers_Cheat_Sheet.html#access-control-allow-origin
- web https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java#L289
- web https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L525
- web https://github.com/advisories/GHSA-hv2w-8mjj-jw22