Security Digest · Vulnerability record
CVE-2025-6545: pbkdf2 returns predictable uninitialized/zero-filled memory for non-normalized or unimplemented algos
Improper Input Validation vulnerability in pbkdf2 allows Signature Spoofing by Improper Validation.
CVSS 9.1 Critical EPSS 0.4% · p38
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.4%, percentile 38: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 38% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
pbkdf2(npm) >= 3.0.10, <= 3.1.2, fixed in 3.1.3. Check your lockfile, including transitive dependencies.
What it is
Improper Input Validation vulnerability in pbkdf2 allows Signature Spoofing by Improper Validation. This vulnerability is associated with program files lib/to-buffer.Js. This issue affects pbkdf2: from 3.0.10 through 3.1.2.
From the GitHub advisory
Summary
This affects both: 1. Unsupported algos (e.g. sha3-256 / sha3-512 / sha512-256) 2. Supported but non-normalized algos (e.g. Sha256 / Sha512 / SHA1 / sha-1 / sha-256 / sha-512)
All of those work correctly in Node.js, but this polyfill silently returns highly predictable ouput
Under Node.js (only with pbkdf2/browser import, unlikely) / Bun (pbkdf2 top-level import is affected), the memory is not zero-filled but is uninitialized, as Buffer.allocUnsafe is used
Under browsers, it just returns zero-filled buffers (Which is also critical, those are completely unacceptable as kdf output and ruin security)
Weakness type: CWE-20.
Product: pbkdf2 (npm) · Assigned by: harborist · Published: 2025-06-23
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| npm | pbkdf2 | >= 3.0.10, <= 3.1.2 | 3.1.3 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| pbkdf2 | 3.0.10 <= 3.1.2 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| harborist | 4.0 | 9.1 Critical | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:H/SI:H/SA:H |
| GitHub | 4.0 | 9.1 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:H/SI:H/SA:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Attack requirements: present (depends on deployment conditions)
- Privileges required: none (no login)
- User interaction: none
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable no, technical impact partial.
- FIRST EPSS (model of 2026-10-21): 0.45% probability of exploitation activity in the next 30 days; percentile 38.
Timeline
- — CVE record last updated
- — CVE record published by harborist
- — GitHub-reviewed advisory GHSA-h7cp-r72f-jxh6 published (critical)
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- github.com github.com
Vulnerability records
- GitHub Advisory GHSA-h7cp-r72f-jxh6 github.com
- CVE.org record CVE-2025-6545 cve.org
- NVD entry CVE-2025-6545 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com