CVE-2025-6547: On Node.js < 3, pbkdf2 silently disregards Uint8Array input, returning static keys
Summary
On historic but declared as supported Node.js versions (0.12-2.x), pbkdf2 silently disregards Uint8Array input
This only affects Node.js <3.0.0, but pbkdf2 claims to: Support Node.js >= 0.12 (and there seems to be ongoing effort in this repo to maintain that) Support Uint8Array input (input is typechecked against Uint8Array, and the error message includes e.g. "Password must be a string, a Buffer, a typed array or a DataView"
Details
The error is in toBuffer method
This vulnerability somehow even made it to tests: https://github.com/browserify/pbkdf2/commit/eb9f97a66ed83836bebc4ff563a1588248708501 There, resultsOld (where mismatch results) are just invalid output generated from empty password/salt instead of the supplied one
PoC
On Node.js/io.js < 3.0.0
console > require('pbkdf2').pbkdf2Sync(new Uint8Array([1,2,3]), new Uint8Array([1,3,4]), 1024, 32, 'sha256') <Buffer 21 53 cd 5b a5 f0 15 39 2f 68 e2 40 8b 21 ba ca 0e dc 7b 20 d5 45 a4 8a ea b5 95 9f f0 be bf 66>
// But that's just a hash of empty data with empty password: > require('pbkdf2').pbkdf2Sync('', '', 1024, 32, 'sha256') <Buffer 21 53 cd 5b a5 f0 15 39 2f 68 e2 40 8b 21 ba ca 0e dc 7b 20 d5 45 a4 8a ea b5 95 9f f0 be bf 66>
// Node.js crypto is fine even on that version: > require('crypto').pbkdf2Sync(new Uint8Array([1,2,3]), new Uint8Array([1,3,4]), 1024, 32, 'sha256') <Buffer 78 10 cc 84 b7 bb 85 cd c8 37 ca 68 da a9 4c 33 db ae c2 3d 5b d4 95 76 da 33 f9 95 ac 51 f4 45>
// Empty hash from Node.js, for comparison > require('crypto').pbkdf2Sync('', '', 1024, 32, 'sha256') <Buffer 21 53 cd 5b a5 f0 15 39 2f 68 e2 40 8b 21 ba ca 0e dc 7b 20 d5 45 a4 8a ea b5 95 9f f0 be bf 66>
Impact
Static hashes being outputted and used as keys/passwords can completely undermine security That said, no one should be using those Node.js versions anywhere now, so I would recommend to just drop them This lib should not pretend to work on those versions while outputting static data though
Just updating to a fixed version is not enough: if anyone was using pbkdf2 lib (do not confuse with Node.js crypto.pbkdf2) or anything depending on it with Node.js/io.js < 3.0.0, recheck where those keys went / how they were used, and take action accordingly
Other sources
Improper Input Validation vulnerability in pbkdf2 allows Signature Spoofing by Improper Validation.This issue affects pbkdf2: <=3.1.2.
— NVD
Improper Input Validation vulnerability in pbkdf2 allows Signature Spoofing by Improper Validation.This issue affects pbkdf2: =3.1.2.
— IBM
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
npm/pbkdf2to a version that resolves this vulnerability.Fixed in 3.1.3 - Upgrade
Upgrade
pbkdf2to a version that resolves this vulnerability.Fixed in 3.1.2 - Configuration
Do not rely on pbkdf2 with Uint8Array input on Node.js/io.js < 3.0.0; the issue is in the `toBuffer` method where `resultsOld` mismatch leads to invalid output generated from empty password/salt instead of the supplied values.
pbkdf2 (toBuffer method) Uint8Array input handling = reject/avoid Uint8Array on Node.js < 3.0.0 - Compensating control
If any deployments still run Node.js/io.js < 3.0.0 (where pbkdf2 silently disregards Uint8Array input and returns static keys), recheck where the derived keys/passwords were used and take action accordingly (treat derived keys/passwords as potentially compromised).
- Operational
For any derived keys/passwords produced on Node.js/io.js < 3.0.0 using Uint8Array input, rotate/re-generate those keys/passwords because pbkdf2 can output static data (static hashes being outputted and used as keys/passwords can undermine security).
Event History
Frequently Asked Questions
What is the severity of CVE-2025-6547?
CVE-2025-6547 is classified as a moderate severity vulnerability due to its potential for signature spoofing.
How do I fix CVE-2025-6547?
To mitigate CVE-2025-6547, upgrade the pbkdf2 package to version 3.1.3 or later.
What impact does CVE-2025-6547 have on my application?
CVE-2025-6547 can allow attackers to perform signature spoofing, compromising the integrity of data.
Which versions of pbkdf2 are affected by CVE-2025-6547?
CVE-2025-6547 affects the pbkdf2 package versions up to and including 3.1.2.
Is CVE-2025-6547 related to other vulnerabilities?
CVE-2025-6547 is specifically related to improper input validation, but may exhibit similar behaviors to other spoofing vulnerabilities.