CVE-2026-64643: CWE-201: Insertion of Sensitive Information Into Sent Data in vercel next.js
Next.js is a React framework for building full-stack web applications. In versions 12.0.0 through 15.5.20 and 16.0.0 through 16.2.10, Next.js applications using App Router, Server Actions (use server) or use cache endpoints can be disclosed bypassing any authentication on the pages where these endpoints are usually used. Server Action IDs can be disclosed to unauthenticated users via publicly served client artifacts (for example, static chunks containing action references). Affected users are applications using App Router and Server Actions. By itself, this disclosure is typically a recon/enumeration primitive; however, it can increase risk when combined with other weaknesses. This issue has been fixed in versions 15.5.21 and 16.2.11.
AI Analysis
Technical Summary
CVE-2026-64643 is an information disclosure vulnerability in Next.js, a React framework, affecting versions >=13.0.0 <15.5.21 and >=16.0.0 <16.2.11. The flaw allows unauthenticated users to obtain Server Action IDs through publicly accessible client artifacts, such as static chunks referencing server actions. This disclosure bypasses authentication on pages using App Router, Server Actions, or cache endpoints. While primarily a reconnaissance issue, it can increase risk if combined with other vulnerabilities. The vulnerability is classified as CWE-201 (Insertion of Sensitive Information Into Sent Data).
Potential Impact
Unauthenticated attackers can access Server Action IDs that are normally protected, potentially enabling further attacks when combined with other vulnerabilities. By itself, this is mainly a reconnaissance vulnerability that reveals sensitive internal identifiers, which may aid attackers in mapping application internals or crafting targeted exploits.
Mitigation Recommendations
This vulnerability has been fixed in Next.js versions 15.5.21 and 16.2.11. Users should upgrade to these or later versions to remediate the issue. No additional mitigation is required if the application is updated accordingly.
CVE-2026-64643: CWE-201: Insertion of Sensitive Information Into Sent Data in vercel next.js
Description
Next.js is a React framework for building full-stack web applications. In versions 12.0.0 through 15.5.20 and 16.0.0 through 16.2.10, Next.js applications using App Router, Server Actions (use server) or use cache endpoints can be disclosed bypassing any authentication on the pages where these endpoints are usually used. Server Action IDs can be disclosed to unauthenticated users via publicly served client artifacts (for example, static chunks containing action references). Affected users are applications using App Router and Server Actions. By itself, this disclosure is typically a recon/enumeration primitive; however, it can increase risk when combined with other weaknesses. This issue has been fixed in versions 15.5.21 and 16.2.11.
CVSS v4.0
Score 6.3medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-64643 is an information disclosure vulnerability in Next.js, a React framework, affecting versions >=13.0.0 <15.5.21 and >=16.0.0 <16.2.11. The flaw allows unauthenticated users to obtain Server Action IDs through publicly accessible client artifacts, such as static chunks referencing server actions. This disclosure bypasses authentication on pages using App Router, Server Actions, or cache endpoints. While primarily a reconnaissance issue, it can increase risk if combined with other vulnerabilities. The vulnerability is classified as CWE-201 (Insertion of Sensitive Information Into Sent Data).
Potential Impact
Unauthenticated attackers can access Server Action IDs that are normally protected, potentially enabling further attacks when combined with other vulnerabilities. By itself, this is mainly a reconnaissance vulnerability that reveals sensitive internal identifiers, which may aid attackers in mapping application internals or crafting targeted exploits.
Mitigation Recommendations
This vulnerability has been fixed in Next.js versions 15.5.21 and 16.2.11. Users should upgrade to these or later versions to remediate the issue. No additional mitigation is required if the application is updated accordingly.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-955p-x3mx-jcvp
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-64643"]
- Ecosystems
- ["npm"]
- Database Specific Severity
- MODERATE
- Cvss Version
- 4.0
Threat ID: 6a616bcd9c2644c7f80dbdb1
Added to database: 07/23/2026, 01:18:05 UTC
Last enriched: 07/30/2026, 15:28:36 UTC
Last updated: 09/05/2026, 10:52:11 UTC
Views: 204
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