---
id: RUSTSEC-2026-0329
title: Auto-Reseeding HMAC-DRBG could panic for some output lengths
summary: Auto-Reseeding HMAC-DRBG could panic for some output lengths
severity: none
vendor: libcrux-hmac-drbg
product: libcrux-hmac-drbg
ecosystem: rust
affected:
  - 'libcrux-hmac-drbg >= 0.0.0-0, < 0.0.2'
patched:
  - libcrux-hmac-drbg 0.0.2
published: '2026-08-03'
updated: '2026-10-07'
sourceUpdated: '2026-10-07T08:30:02.846769865Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/RUSTSEC-2026-0329'
references:
  - url: 'https://crates.io/crates/libcrux-hmac-drbg'
  - url: 'https://rustsec.org/advisories/RUSTSEC-2026-0329.html'
  - url: 'https://github.com/celabshq/libcrux/pull/1558'
tags:
  - osv
  - rust
ingestedAt: '2026-10-08T07:34:51.739Z'
---

## Overview

The automatically reseeding implementations of HMAC-DRBG would panic if called with a desired non-zero output length cleanly divisible by `65_536`, the maximum number of output bytes that can be generated before reseeding has to happen.

# Impact

An application relying on `libcrux-hmac-drgb` to provide randomness of byte length a non-zero integer multiple of `65_536` in a single call to `fill_bytes` would panic.

Any calls with output buffer lengths not cleanly divisible by `65_536` are not affected.

# Mitigation

With release the release of version `0.0.2` of `libcrux-hmac-drbg` this bug has been fixed and reseeding DRBG implementations can be used with arbitrary output lengths.

We recommend users upgrade to `libcrux-hmac-drbg` version `0.0.2`.

## Affected packages

- `libcrux-hmac-drbg >= 0.0.0-0, < 0.0.2`

## Remediation

Upgrade to a patched release:

- `libcrux-hmac-drbg 0.0.2`