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CVE-2026-34742
high
CVSS 8.1
Vulnerability in github.com/modelcontextprotocol/go-sdk (CVE-2026-34742)
Summary
vulnerability in github.com/modelcontextprotocol/go-sdk (CVE-2026-34742). Confidential information can be exposed externally. Mitigation: upgrade to `1.4.0` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-34742** has been found in github.com/modelcontextprotocol/go-sdk.
Confidential information can be exposed externally. CVSS score: 8.1/10.
What to do: upgrade github.com/modelcontextprotocol/go-sdk to **1.4.0** or later.
If unsure, ask your IT team or search "github.com/modelcontextprotocol/go-sdk CVE-2026-34742" on the vendor's site.
CVE-2026-34742 (github.com/modelcontextprotocol/go-sdk) — CWE-1188 / CVSS v3 8.1
Attack vector: remote (network-reachable) / unauthenticated
Patched: `1.4.0` — 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-1188) exists in github.com/modelcontextprotocol/go-sdk.
📍 Affected scope
github.com/modelcontextprotocol/go-sdk — .
🔥 Severity
Severity: High (CVSS 8.1/10). Confidential information can be exposed externally
🔧 How to fix
Update to **1.4.0**.
🛡️ 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 'github.com/modelcontextprotocol/go-sdk' .` 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 'github.com/modelcontextprotocol/go-sdk' . | 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/go-sdk` 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 github.com/modelcontextprotocol/go-sdk to 1.4.0ステージング環境で 1.4.0 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
go
github.com/modelcontextprotocol/go-sdk
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.4.0"}]}]
References
- advisory https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6
- advisory https://nvd.nist.gov/vuln/detail/CVE-2026-34742
- patch https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d
- patch https://github.com/modelcontextprotocol/go-sdk/pull/760
- web https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0
- web 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- web 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- web 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- web 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- web https://github.com/advisories/GHSA-xw59-hvm2-8pj6