CVE-2026-102414

pbkdf2 rehashes long passwords on every iteration, enabling denial of service

Published Sep 29, 2026 CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed
Description
pbkdf2 through 3.1.6 re-hashes passwords longer than the digest's block size on every iteration in its JavaScript fallback (lib/sync.js). A password longer than the block size (64 bytes, or 128 bytes for sha384 and sha512) is passed to HMAC as the key on every iteration, and HMAC hashes such keys in full each time. Cost is therefore O(iterations × password length), and a long password can block the event loop. The fallback is used by pbkdf2Sync and pbkdf2 on Node.js before 0.12, on Bun (1.0.0 through 1.1.34, and 1.2.6 and later), and on Deno 2.9.0 and later, because their native pbkdf2Sync fails the library's feature check. It is also used when lib/sync.js is imported directly. Node.js 0.12 and later, and browser builds (which use lib/sync-browser.js), are not affected. Applications that enforce a reasonable maximum password length are not meaningfully affected.

Remediation

Vendor Solution

Upgrade to a version of pbkdf2 that includes the fix, which pre-hashes passwords longer than the digest block size once before iterating, or, enforce literally any reasonable maximum password length before calling pbkdf2.


Vendor Workaround

Enforce a maximum password length (for example, 1024 bytes) before calling pbkdf2, or call the runtime's native crypto.pbkdf2Sync directly.

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Github GHSA Github GHSA GHSA-477h-4r7f-fvrx pbkdf2 rehashes long passwords on every iteration, enabling denial of service
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Browserify
Browserify pbkdf2
Vendors & Products Browserify
Browserify pbkdf2
Type Values Removed Values Added
Description pbkdf2 through 3.1.6 re-hashes passwords longer than the digest's block size on every iteration in its JavaScript fallback (lib/sync.js). A password longer than the block size (64 bytes, or 128 bytes for sha384 and sha512) is passed to HMAC as the key on every iteration, and HMAC hashes such keys in full each time. Cost is therefore O(iterations × password length), and a long password can block the event loop. The fallback is used by pbkdf2Sync and pbkdf2 on Node.js before 0.12, on Bun (1.0.0 through 1.1.34, and 1.2.6 and later), and on Deno 2.9.0 and later, because their native pbkdf2Sync fails the library's feature check. It is also used when lib/sync.js is imported directly. Node.js 0.12 and later, and browser builds (which use lib/sync-browser.js), are not affected. Applications that enforce a reasonable maximum password length are not meaningfully affected.
Title pbkdf2 rehashes long passwords on every iteration, enabling denial of service
Weaknesses CWE-400
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L'}

cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
harborist
Published
Updated
Sep 30, 2026, 3:17 PM
Reserved
Sep 29, 2026, 2:06 AM
Status
Deferred
Published
Sep 29, 2026, 4:17 AM
Modified
Sep 30, 2026, 5:32 PM