Vulnerability in engine.io (CVE-2026-59724)
Summary
Vulnerability in engine.io (CVE-2026-59724). Risk of unauthorized operations or information disclosure. Exploitable via __proto__. Mitigation: upgrade to 6.6.7 or later.
Original description
The description as published by the source.
Socket.IO enables bidirectional and low-latency communication for every platform. From 6.5.0 before 6.6.7, Engine.IO servers with WebTransport enabled can resolve a crafted session ID such as proto through an inherited property of the clients object during WebTransport upgrade handling, causing a TypeError and denial of service. This issue is fixed in version 6.6.7.
Source: NIST National Vulnerability Database 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-2026-59724 has been found in engine.io.
Attackers can target a specific entry point like __proto__ over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade engine.io to 6.6.7 or later.
If unsure, ask your IT team or search "engine.io CVE-2026-59724" on the vendor's site.
CVE-2026-59724 (engine.io) — CWE-20 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: __proto__ / TypeError / webtransport
Patched: 6.6.7 — 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-20) exists in engine.io. Attackers reach the vulnerable code path via __proto__ without authentication.
Check the vendor advisory for the affected versions of engine.io. Attack surface: __proto__ / TypeError / webtransport.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 6.6.7.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'engine.io' . 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
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1Identify exposure identify
grep -r 'engine.io' . | 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
engine.ioを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade engine.io to 6.6.7ステージング環境で 6.6.7 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を含めること。
-
3Post-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。本番ではアクセスログ・WAF 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
- patch github.com
- web github.com
- web github.com