node-forge versions through 1.4.0 contain a critical vulnerability in RSA PKCS#1 v1.5 signature verification. The library fails to validate the element count in nested DigestAlgorithm sequences, allowing attackers to embed garbage bytes inside the DigestAlgorithm sequence. This flaw enables forging of valid signatures for arbitrary messages when low-exponent RSA keys are used. The vulnerability is identified as an incomplete fix for a prior related issue CVE-2026-33894. Affected source files include asn1.js and rsa.js in the node-forge library. The issue is tracked under GHSA-ppp5-5v6c-4jwp on GitHub and has been reported via VulnCheck advisories. Users of node-forge are advised to review and apply any available patches or mitigations promptly.
