Cross-Site Scripting (XSS) in next (CVE-2026-44580)
Summary
Cross-site scripting in next (CVE-2026-44580). Risk of unauthorized operations or information disclosure. Exploitable via beforeInteractive. Mitigation: upgrade to 16.2.5 or later.
Original description
The description as published by the source.
Impact
Applications that use beforeInteractive scripts together with untrusted content can be vulnerable to cross-site scripting. In affected versions, serialized script content was not escaped safely before being embedded into the document, which could allow attacker-controlled input to break out of the intended script context and execute arbitrary JavaScript in a visitor's browser.
Fix
We now HTML-escape serialized beforeInteractive script content before embedding it into the page, preventing attacker-controlled content from breaking out of the inline script boundary.
Workarounds
If you cannot upgrade immediately, do not pass untrusted data into beforeInteractive scripts. If that pattern is unavoidable, sanitize or escape the content before embedding it.
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-2026-44580 has been found in next.
Attackers can target a specific entry point like beforeInteractive over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.1/10.
What to do: upgrade next to 16.2.5 or later.
If unsure, ask your IT team or search "next CVE-2026-44580" on the vendor's site.
CVE-2026-44580 (next) — CWE-79 / CVSS v3 6.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: beforeInteractive
Patched: 16.2.5 — apply immediately
Workaround: If you cannot upgrade immediately, do not pass untrusted data into beforeInteractive scripts.
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 beforeInteractive without authentication.
Check the vendor advisory for the affected versions of next. Attack surface: beforeInteractive.
Severity: Medium (CVSS 6.1/10). Risk of unauthorized operations or information disclosure.
Update to 16.2.5.
Workaround: If you cannot upgrade immediately, do not pass untrusted data into beforeInteractive scripts.
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
-
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 temporary workaround mitigate
If you cannot upgrade immediately, do not pass untrusted data into `beforeInteractive` scripts.パッチが適用されるまでの応急処置として、If you cannot upgrade immediately, do not pass untrusted data into
beforeInteractivescripts. を実施。回避策の副作用 (機能低下) を確認した上で。 -
3Apply patch patch
Upgrade next to 16.2.5ステージング環境で 16.2.5 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。
-
4Post-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
- web github.com
- web github.com