Vulnerability in deno (CVE-2026-49411)
Summary
Vulnerability in deno (CVE-2026-49411). Confidential information can be exposed externally. Exploitable via Host. Mitigation: upgrade to 2.8.0 or later.
Original description
The description as published by the source.
Summary
Deno's network permission model is designed so that --deny-net rules apply to the resolved IP address of a destination, not just the literal string supplied by the caller. That means --deny-net=127.0.0.1 (or --deny-net=127.0.0.0/8) is expected to block any attempt to reach loopback, regardless of how the hostname is spelled.
On affected versions, the Node.js compatibility TCP path checked the permission against the original hostname string before resolution and then did not re-check after resolution. A caller could therefore pass a numeric alias of an IP address (for example the decimal integer 2130706433 or the hex form 0x7f000001, both of which resolve to 127.0.0.1) and reach the denied destination through node:net.connect or node:http.request's { host, port } options form.
The native Deno.connect(), fetch(), and URL-string variants of node:http.request("http://...") were not affected, because they either re-checked permissions after resolution or normalized the hostname through the URL parser before checking.
Proof of concept
Run on Deno 2.7.14, with a local TCP listener on 127.0.0.1::
import net from "node:net";
// --allow-net + --deny-net=127.0.0.0/8
// (or even --deny-net=127.0.0.1:)
net.connect({ host: "2130706433", port: PORT }); // CONNECTED ❌
net.connect({ host: "0x7f000001", port: PORT }); // CONNECTED ❌
net.connect({ host: "127.0.0.1", port: PORT }); // denied ✅
The same primitive…
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-2026-49411 has been found in deno.
Attackers can target a specific entry point like Host over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 6.5/10.
What to do: upgrade deno to 2.8.0 or later.
If unsure, ask your IT team or search "deno CVE-2026-49411" on the vendor's site.
CVE-2026-49411 (deno) — CWE-284 / CVSS v3 6.5
Attack vector: local / no user interaction
Attack surface: Host / undici / Deno.connect / Deno.connectTls
Patched: 2.8.0 — 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.
A vulnerability (CWE-284) exists in deno. Attackers reach the vulnerable code path via Host.
Check the vendor advisory for the affected versions of deno. Attack surface: Host / undici / Deno.connect / Deno.connectTls.
Severity: Medium (CVSS 6.5/10). Confidential information can be exposed externally.
Update to 2.8.0.
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 'deno' . 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 'deno' . | 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
deno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 deno to 2.8.0ステージング環境で 2.8.0 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 nvd.nist.gov
- package github.com
- web github.com
- web github.com