---
id: CVE-2026-62239
title: >-
  FlashAttention through 2.8.3.post1, fixed in commit 0816ef1, contains a
  symlink attack vulnerability in the download_and_copy() function within
  hopper/setup.py that extracts NVIDIA toolchain archives without validating
  symlinks or filter…
summary: >-
  FlashAttention through 2.8.3.post1, fixed in commit 0816ef1, contains a
  symlink attack vulnerability in the download_and_copy() function within
  hopper/setup.py that extracts NVIDIA toolchain archives without validating
  symlinks or filter…
severity: medium
cvss: 6.6
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N'
cwe:
  - CWE-59
vendor: Dao-AILab
product: flash-attention
affected:
  - flash-attention <= 2.8.3.post1
published: '2026-07-13'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T18:16:56.493'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-62239'
references:
  - url: >-
      https://github.com/Dao-AILab/flash-attention/commit/0816ef12f424c6ec94b057a72c275b14f6e6edb2
    label: disclosure@vulncheck.com
  - url: 'https://github.com/Dao-AILab/flash-attention/issues/2637'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/Dao-AILab/flash-attention/pull/2702'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/flashattention-symlink-attack-via-tarfile-extractall-in-hopper-setup-py
    label: disclosure@vulncheck.com
  - url: 'https://github.com/Dao-AILab/flash-attention/issues/2637'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-07-14T12:53:41.369813Z'
epss: 0.00164
epssPercentile: 0.04944
ingestedAt: '2026-09-17T18:25:15.976Z'
---

## Overview

FlashAttention through 2.8.3.post1, fixed in commit 0816ef1, contains a symlink attack vulnerability in the download_and_copy() function within hopper/setup.py that extracts NVIDIA toolchain archives without validating symlinks or filtering tar members. A local attacker can pre-plant a symlink in the predictable cache directory to redirect extracted binaries to an attacker-chosen location, enabling arbitrary file write with victim privileges during build time.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.