---
id: CVE-2026-32829
title: lz4_flex is a pure Rust implementation of LZ4 compression/decompression
summary: >-
  lz4_flex is a pure Rust implementation of LZ4 compression/decompression. In
  versions 0.11.5 and below, and 0.12.0,  decompressing invalid LZ4 data can
  leak sensitive information from uninitialized memory or from previous
  decompression op…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-201
  - CWE-823
vendor: pseitz
product: lz4_flex
affected:
  - lz4_flex < 0.11.6
  - lz4_flex = 0.12.0
patched:
  - lz4_flex 0.11.6
published: '2026-03-20'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T12:17:49.007'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-32829'
references:
  - url: >-
      https://github.com/PSeitz/lz4_flex/commit/055502ee5d297ecd6bf448ac91c055c7f6df9b6d
    label: security-advisories@github.com
  - url: 'https://github.com/PSeitz/lz4_flex/security/advisories/GHSA-vvp9-7p8x-rfvv'
    label: security-advisories@github.com
  - url: 'https://rustsec.org/advisories/RUSTSEC-2026-0041.html'
    label: security-advisories@github.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:11800'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:16354'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:19712'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:22862'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-32829'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2448271'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32829.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-32829'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-32829'
  - url: 'https://github.com/PSeitz/lz4_flex'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-03-21T03:02:22.812939Z'
scores:
  nvd: 7.5
  cna: 8.2
  vendor: 7.5
epss: 0.00691
epssPercentile: 0.50725
ingestedAt: '2026-07-14T12:36:48.064Z'
---

## Overview

lz4_flex is a pure Rust implementation of LZ4 compression/decompression. In versions 0.11.5 and below, and 0.12.0,  decompressing invalid LZ4 data can leak sensitive information from uninitialized memory or from previous decompression operations. The library fails to properly validate offset values during LZ4 "match copy operations," allowing out-of-bounds reads from the output buffer. The block-based API functions (`decompress_into`, `decompress_into_with_dict`, and others when `safe-decode` is disabled) are affected, while all frame APIs are unaffected. The impact is potential exposure of sensitive data and secrets through crafted or malformed LZ4 input. This issue has been fixed in versions 0.11.6 and 0.12.1.

## Affected

- `lz4_flex < 0.11.6`
- `lz4_flex = 0.12.0`

## Remediation

Upgrade past the affected range:

- `lz4_flex 0.11.6`

## Vendor advisories

- **RHSA-2026:22862** · Red Hat · fixed in: Logging Subsystem for Red Hat OpenShift 6.4 · released 2026-06-03 · [advisory](https://access.redhat.com/errata/RHSA-2026:22862)
- **RHSA-2026:16354** · Red Hat · fixed in: Logging Subsystem for Red Hat OpenShift 6.5 · released 2026-05-12 · [advisory](https://access.redhat.com/errata/RHSA-2026:16354)
- **RHSA-2026:11800** · Red Hat · fixed in: Logging for Red Hat OpenShift 6.2 · released 2026-04-29 · [advisory](https://access.redhat.com/errata/RHSA-2026:11800)
- **RHSA-2026:19712** · Red Hat · fixed in: Red Hat OpenShift AI 3.3 · released 2026-05-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:19712)
- **Red Hat VEX** · Important · affected: OpenShift Lightspeed, Red Hat Ansible Automation Platform 2 · no fix planned: OpenShift Lightspeed, Red Hat Ansible Automation Platform 2 · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32829.json)