CVE-2026-64643
Description
A flaw was found in Next.js. Unauthenticated users can exploit this vulnerability by accessing publicly served client artifacts, which may disclose Server Action IDs. This bypasses authentication on pages where these endpoints are used, leading to information disclosure. While primarily an enumeration primitive, this disclosure can increase overall risk when combined with other vulnerabilities.
Statement
This Moderate information disclosure vulnerability in Next.js applications allows unauthenticated users to obtain Server Action IDs from publicly served client artifacts. While primarily a reconnaissance primitive, this exposure could increase overall risk when chained with other weaknesses. Red Hat products and services that incorporate Next.js, such as Red Hat AMQ, Red Hat Enterprise Linux AI, and cloud.redhat.com offerings, are affected.
Mitigation
Upstream advises that applications should never assume authentication claims at the `use server` (Server Action) or `use cache` boundary: always perform authentication checks within the Server Action or cached function itself rather than relying on page-level authentication or on Server Action IDs remaining secret. In addition, the upstream fix is available in Next.js 15.5.21 and 16.2.11, and upgrading to a fixed version removes the exposure.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | 5.3 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | Low | Low | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Files or Directories; Read Memory; Read Application Data
Sensitive data may be exposed to attackers.
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