Next.js: Denial of Service in App Router using Server Actions (CVE-2026-64641)
Next.js versions using the App Router with Server Actions are vulnerable to a denial of service condition caused by crafted requests that induce excessive CPU usage. This blocks processing of further requests in the same process, impacting availability. Applications using the Pages Router or not using Server Actions are not affected. No workaround exists other than upgrading to a fixed version.
AI Analysis
Technical Summary
CVE-2026-64641 is a denial of service vulnerability in Next.js applications that use the App Router with at least one Server Action. Crafted requests can cause excessive CPU consumption, blocking the processing of subsequent requests in the same process. This vulnerability affects Next.js versions >=13.0.0 <15.5.21 and >=16.0.0 <16.2.11. Applications using the Pages Router or those without Server Actions are not vulnerable. No workaround is available besides upgrading to a patched version.
Potential Impact
Successful exploitation results in denial of service by causing excessive CPU usage, which blocks further request processing in the affected Next.js process. This leads to degraded availability of the application until the process is restarted or upgraded.
Mitigation Recommendations
Upgrade Next.js to a version later than 15.5.21 for the 13.x and 15.x branches, or later than 16.2.11 for the 16.x branch. No other workaround exists. Applications not using the App Router with Server Actions are not vulnerable.
Next.js: Denial of Service in App Router using Server Actions (CVE-2026-64641)
Description
Next.js versions using the App Router with Server Actions are vulnerable to a denial of service condition caused by crafted requests that induce excessive CPU usage. This blocks processing of further requests in the same process, impacting availability. Applications using the Pages Router or not using Server Actions are not affected. No workaround exists other than upgrading to a fixed version.
CVSS v4.0
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-64641 is a denial of service vulnerability in Next.js applications that use the App Router with at least one Server Action. Crafted requests can cause excessive CPU consumption, blocking the processing of subsequent requests in the same process. This vulnerability affects Next.js versions >=13.0.0 <15.5.21 and >=16.0.0 <16.2.11. Applications using the Pages Router or those without Server Actions are not vulnerable. No workaround is available besides upgrading to a patched version.
Potential Impact
Successful exploitation results in denial of service by causing excessive CPU usage, which blocks further request processing in the affected Next.js process. This leads to degraded availability of the application until the process is restarted or upgraded.
Mitigation Recommendations
Upgrade Next.js to a version later than 15.5.21 for the 13.x and 15.x branches, or later than 16.2.11 for the 16.x branch. No other workaround exists. Applications not using the App Router with Server Actions are not vulnerable.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-m99w-x7hq-7vfj
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-64641"]
- Ecosystems
- ["npm"]
- Database Specific Severity
- HIGH
- Cvss Version
- 4.0
Threat ID: 6a616bcf9c2644c7f80dbeac
Added to database: 07/23/2026, 01:18:07 UTC
Last enriched: 07/23/2026, 01:22:12 UTC
Last updated: 07/23/2026, 01:35:11 UTC
Views: 4
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