CVE-2025-6545: pbkdf2 Predictable Key Generation Critical Vulnerability

CVE-2025-6545 identifies a critical improper input validation vulnerability in the pbkdf2 npm package that enables attackers to exploit cryptographic key derivation weaknesses by causing the library to return predictable zero-filled or uninitialized memory buffers instead of cryptographically secure keys for non-normalized or unsupported algorithm names. This vulnerability affects pbkdf2 versions 3.0.10 through 3.1.2, achieving a CVSS score of 9.1 (Critical severity) with EPSS percentile of 27.5 indicating extremely high exploit risk for JavaScript applications and browser-based crypto implementations utilizing pbkdf2 for key derivation in bundled environments, crypto-browserify polyfills, and Node.js/Bun runtime contexts. The vulnerability details reveal that inadequate algorithm name validation causes the library to silently fail when processing non-exact algorithm name matches like "SHA256", "sha3-512", or "RIPEMD-160", returning dangerous zero-filled buffers in browsers or uninitialized memory in Node.js/Bun environments, creating substantial exploit risk for web applications, cryptographic libraries, and bundled JavaScript applications that depend on pbkdf2 for secure key generation without proper algorithm name normalization. The root cause analysis reveals that the vulnerability stems from hardcoded algorithm name mapping in the internal HMAC implementation where inadequate case-sensitive string matching and missing algorithm support causes silent failures during key derivation processing, classified as CWE-20 (Improper Input Validation). The vulnerability specifically affects the key derivation workflow introduced in commit 9699045c37a07f8319cfb8d44e2ff4252d7a7078 where the replacement of create-hmac library with internal implementation fails to handle algorithm name variations, enabling attackers to exploit known exploited vulnerabilities targeting cryptographic key generation mechanisms to compromise applications that unknowingly generate predictable keys for sensitive operations. Mitigation steps require immediate upgrading to pbkdf2 version 3.1.3 or later which implements proper algorithm name validation and error handling, followed by comprehensive security audits to identify and regenerate any compromised keys that may have been generated using vulnerable algorithm name variations. Organizations should prioritize identifying JavaScript applications using vulnerable pbkdf2 versions in bundled environments or crypto polyfills, implement strict algorithm name validation and normalization before key derivation operations, audit all previously generated cryptographic keys for potential compromise especially those using non-standard algorithm name formats, consider migrating to modern crypto.subtle APIs for browser environments to avoid polyfill vulnerabilities, and maintain updated vulnerability database records to track similar cryptographic library vulnerabilities that could compromise application security through predictable key generation and broader security implications for web applications relying on JavaScript cryptographic implementations with insufficient input validation controls.