Vulnerability in unleash-server (CVE-2026-63466)
Summary
Vulnerability in unleash-server (CVE-2026-63466). Risk of unauthorized operations or information disclosure. Exploitable via POST /invite/. Mitigation: upgrade to 8.0.3 or later.
Original description
The description as published by the source.
Vulnerability Details
File: src/lib/addons/feature-event-formatter-md.ts
Line: 355 (in v8.0.1; format() method)
Root Cause
FeatureEventFormatterMd.format() does:
Mustache.escape = (text) => text;
const text = Mustache.render(action, context);
mustache (pinned ^4.2.0, confirmed installed 4.2.0) keeps escape as a module-level singleton (mustache.js: mustache.escape = escapeHtml;), read by every Mustache.render() call in the process unless a per-call config.escape override is passed (var escape = this.getConfigEscape(config) || mustache.escape;). Node's module cache guarantees every import Mustache from 'mustache' in the process — feature-event-formatter-md.ts, email-service.ts, webhook.ts, datadog.ts, new-relic.ts — shares the same object instance.
This assignment therefore permanently disables HTML escaping for every other Mustache.render() call in the same Node process (including email-service.ts templates) from the moment any single notification addon (Webhook, Slack legacy, Microsoft Teams, Datadog, New Relic) first formats any event, for the remaining lifetime of the process.
feature-event-formatter-md-events.ts (EVENT_MAP) confirms the blast radius: nearly every event's action template interpolates attacker-controlled values with single-mustache (intended-to-be-escaped) syntax, most importantly {{user}}, which is event.createdBy — the acting account's username (or email if set; `…
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-2026-63466 has been found in unleash-server.
Attackers can target a specific entry point like POST /invite/ over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.1/10.
What to do: upgrade unleash-server to 8.0.3 or later.
If unsure, ask your IT team or search "unleash-server CVE-2026-63466" on the vendor's site.
CVE-2026-63466 (unleash-server) — CWE-116 / CVSS v3 4.1
Attack vector: remote (network-reachable)
Attack surface: POST /invite/ / mustache / escape / mustache.js
Patched: 8.0.3 — 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.
A vulnerability (CWE-116) exists in unleash-server. Attackers reach the vulnerable code path via POST /invite/.
Check the vendor advisory for the affected versions of unleash-server. Attack surface: POST /invite/ / mustache / escape / mustache.js.
Severity: Medium (CVSS 4.1/10). Risk of unauthorized operations or information disclosure.
Update to 8.0.3.
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 /invite/ requests with malformed payloads or SQL meta-characters. Run grep -r 'unleash-server' . 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 'unleash-server' . | 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
unleash-server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 /invite/' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /invite/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 unleash-server to 8.0.3ステージング環境で 8.0.3 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 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 /invite/ 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
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com