Authorization Flaw in deno (CVE-2026-49983)
Summary
Vulnerability in deno (CVE-2026-49983). Risk of unauthorized operations or information disclosure. Exploitable via env. Mitigation: upgrade to 2.8.1 or later.
Original description
The description as published by the source.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, environment access is gated by the env permission. You can deny it with --deny-env, or restrict it to a specific allowlist with --allow-env=FOO,BAR. The expectation is that a program running without env permission cannot change process.env. process.loadEnvFile() (the Node-compatible API for loading variables from a .env file) does not honor this. It only checks that the program has read permission for the dotenv file, then writes every key in that file into the process environment — even when env access is denied. In effect, --allow-read plus a writable or attacker-controlled .env file is enough to defeat --deny-env. This vulnerability is fixed in 2.8.1.
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-2026-49983 has been found in deno.
Attackers can target a specific entry point like env over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.2/10.
What to do: upgrade deno to 2.8.1 or later.
If unsure, ask your IT team or search "deno CVE-2026-49983" on the vendor's site.
CVE-2026-49983 (deno) — CWE-863 / CVSS v3 5.2
Attack vector: local / no user interaction
Attack surface: env / process.env
Patched: 2.8.1 — 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.
Incorrect authorization (CWE-863) exists in deno. Attackers reach the vulnerable code path via env.
Check the vendor advisory for the affected versions of deno. Attack surface: env / process.env.
Severity: Medium (CVSS 5.2/10). Risk of unauthorized operations or information disclosure.
Update to 2.8.1.
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
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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 2.8.1ステージング環境で 2.8.1 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。
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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
- web github.com