CVE-2026-123867
Description
A flaw was found in Node.js. When a Transport Layer Security (TLS) server configures a host-specific client Certificate Authority (CA) without providing an associated server certificate, the per-host client validation settings fail to apply. Consequently, the connection silently falls back to trusting the default client CA. A remote client authorized only for the default host can exploit this flaw to bypass mutual TLS (mTLS) restrictions and gain unauthorized access to protected hostnames.
Statement
This vulnerability is rated as having Moderate impact because successful exploitation requires a non-standard configuration and existing authorized client credentials, restricting the flaw to cross-tenant boundary traversal rather than arbitrary unauthenticated access. In standard Red Hat enterprise environments, Node.js applications enforcing mutual TLS typically either configure dedicated server certificates for each virtual host or terminate TLS upstream at an API gateway or reverse proxy. The impact is therefore limited to specific deployments that rely on runtime SNI-based client CA switching without defining host-specific server certificates.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
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 | 4.2 | N/A | 4.2 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | Low |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
cve.org: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
Understanding the Weakness (CWE)
Integrity,Authentication
Technical Impact: Bypass Protection Mechanism; Gain Privileges or Assume Identity
When a certificate is invalid or malicious, it might allow an attacker to spoof a trusted entity by interfering in the communication path between the host and client. The product might connect to a malicious host while believing it is a trusted host, or the product might be deceived into accepting spoofed data that appears to originate from a trusted host.
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