A flaw in node-forge caused the library to ignore the X.509 pathLenConstraint field of a CA certificate when that certificate lacked a keyUsage extension. This weakness, identified as CWE‑295, allows a chain to be constructed that exceeds the declared maximum depth yet still passes the library’s verifyCertificateChain() check. As a result, applications that rely on node-forge for certificate validation may trust a chain of certificates that should be rejected, potentially leading to unauthorized network access or credential compromise.

The issue affects the digitalbazaar:forge library (commonly known as node-forge). Versions prior to 1.4.1 are impacted; the problem is fixed in v1.4.1 and later releases.

The CVSS score of 5.9 indicates a moderate severity. Exploitation requires the attacker to possess a private CA key or a subordinate CA certificate from a path‑length‑constrained CA that does not include keyUsage, and to chain it to a root trusted by the application. Such conditions are more likely to arise in private PKIs where keyUsage was omitted. While documented exploitation is not considered high‑probability, the lack of an EPSS score and absence from CISA KEV suggest no widely‑available exploits are known. Nevertheless, the vulnerability can still enable enterprises to mistakenly accept certificates that violate intended trust boundaries, recommending prompt remediation.