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pbkdf2 silently disregards Uint8Array input, returning static keys

Critical severity GitHub Reviewed Published Jun 23, 2025 in browserify/pbkdf2 • Updated Jun 23, 2025

Package

npm pbkdf2 (npm)

Affected versions

<= 3.1.2

Patched versions

3.1.3

Description

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: browserify/pbkdf2@eb9f97a
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

> 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

References

@ljharb ljharb published to browserify/pbkdf2 Jun 23, 2025
Published by the National Vulnerability Database Jun 23, 2025
Published to the GitHub Advisory Database Jun 23, 2025
Reviewed Jun 23, 2025
Last updated Jun 23, 2025

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity High
Attack Requirements Present
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity High
Availability None
Subsequent System Impact Metrics
Confidentiality High
Integrity High
Availability High

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(26th percentile)

Weaknesses

CVE ID

CVE-2025-6547

GHSA ID

GHSA-v62p-rq8g-8h59

Source code

Credits

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