# CVE-2025-6545: pbkdf2 cryptographic library returns predictable zero-filled output for non-normalized algorithms

Source: https://junglewise.ai/threats/cve-2025-6545-pbkdf2-cryptographic-library-returns-predictable-zero-filled  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-06-23. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2025-6545 · Severity: medium · CVSS 4 · Published 2025-06-23

The pbkdf2 JavaScript library used in browsers and bundled applications silently returns predictable, zero-filled buffers when deriving cryptographic keys with unsupported or non-normalized algorithm names (e.g., "SHA-256" instead of "sha256"), even though these algorithms work correctly in Node.js. This means applications using variant algorithm names receive weak, guessable key material instead of proper cryptographic output, severely compromising password-based encryption, authentication tokens, and other secrets derived through pbkdf2.

Technologies: [pbkdf2 (npm)](https://junglewise.ai/threats/technologies/pbkdf2). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2025-6545 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-6545 being exploited in the wild.

**How severe is CVE-2025-6545?** Medium severity, with a CVSS score of 4, published 23 June 2025.

**Which products and versions are affected?** pbkdf2 (npm) SEMVER:introduced=3.0.10,fixed=3.1.3.

**Is there a fix for CVE-2025-6545?** Yes. pbkdf2 (npm): upgrade to 3.1.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2025-6545 attacked?** It is attacked over the network or with local access, in a software library.

**Am I affected by CVE-2025-6545?** Check whether you run pbkdf2 (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- pbkdf2 (npm): upgrade to 3.1.3 or later

  ```sh
  npm install pbkdf2@3.1.3
  ```


## Technical details

This is an input validation and cryptographic fallback bug in the pbkdf2 npm package (versions 3.0.10 to 3.1.2). The vulnerable component fails to normalize algorithm names (e.g., accepting "Sha256" or "SHA-256" in addition to the canonical "sha256") or validate against unsupported algorithms (e.g., "sha3-512", "blake2b512"). When an unknown or non-normalized name is passed, the library returns a zero-filled buffer in browsers or uninitialized memory via Buffer.allocUnsafe in Node.js/Bun, rather than throwing an error. The attack vector is application-level: developers unknowingly passing variant algorithm names or attempting to use unsupported but theoretically compatible algorithms receive completely predictable output. No network access, authentication, or user interaction is required—the flaw triggers silently on any call with a non-whitelisted algorithm string. The patch (version 3.1.3+) enforces strict algorithm name validation.

## Affected products

- browserify pbkdf2 >=3.0.10, <=3.1.2

## Identifiers

- CVE-2025-6545
- GHSA-h7cp-r72f-jxh6

## Timeline

- 2025-06-23: disclosed: Advisory published GHSA-h7cp-r72f-jxh6 and CVE-2025-6545
- 2025-06-23: patched: Fix released in pbkdf2 version 3.1.3+

## References

- [https://github.com/browserify/pbkdf2/security/advisories/GHSA-h7cp-r72f-jxh6](https://github.com/browserify/pbkdf2/security/advisories/GHSA-h7cp-r72f-jxh6)

## Related threats

- [pbkdf2 rehashes long passwords on every iteration, enabling denial of service](https://junglewise.ai/threats/cve-2026-102414-pbkdf2-through-3-1-6-re-hashes-passwords-longer-than-the-digest)
- [pbkdf2 Uint8Array input handling produces static keys](https://junglewise.ai/threats/cve-2025-6547-pbkdf2-uint8array-input-handling-produces-static-keys)