Cross-Site Scripting (XSS) in next (CVE-2021-39178)
Summary
Cross-site scripting in next (CVE-2021-39178). Risk of unauthorized operations or information disclosure. Exploitable via next.config.js. Mitigation: upgrade to 11.1.1 or later.
Original description
The description as published by the source.
Next.js is a React framework. Versions of Next.js between 10.0.0 and 11.0.0 contain a cross-site scripting vulnerability. In order for an instance to be affected by the vulnerability, the next.config.js file must have images.domains array assigned and the image host assigned in images.domains must allow user-provided SVG. If the next.config.js file has images.loader assigned to something other than default or the instance is deployed on Vercel, the instance is not affected by the vulnerability. The vulnerability is patched in Next.js version 11.1.1.
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
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-2021-39178 has been found in next.
Attackers can target a specific entry point like next.config.js over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade next to 11.1.1 or later.
If unsure, ask your IT team or search "next CVE-2021-39178" on the vendor's site.
CVE-2021-39178 (next) — CWE-79
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: next.config.js / images.domains / images.loader
Patched: 11.1.1 — 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.
Cross-site scripting (XSS) (CWE-79) exists in next. Attackers reach the vulnerable code path via next.config.js without authentication.
Check the vendor advisory for the affected versions of next. Attack surface: next.config.js / images.domains / images.loader.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 11.1.1.
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 'next' . 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 'next' . | 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
next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 next to 11.1.1ステージング環境で 11.1.1 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。
-
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
- patch github.com
- patch github.com
- web github.com
- web github.com