Symlink Attack Vulnerability in FlashAttention by Dao-AILab
CVE-2026-62239

5.3MEDIUM

Key Information:

Vendor

Dao-ailab

Status
Flash-attention
Vendor
CVE Published:
13 July 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-62239?

The FlashAttention product from Dao-AILab, specifically version 2.8.3.post1, is compromised by a symlink attack vulnerability within the download_and_copy() function of hopper/setup.py. This flaw arises as the software extracts NVIDIA toolchain archives without adequate validation of symlinks or proper filtering of tar members. An attacker with local access could pre-place a symlink in a predictable cache directory, allowing for the potential redirection of extracted binaries to an arbitrary location of their choosing. This ultimately results in arbitrary file write access with the privileges of the user during the build process.

Affected Version(s)

flash-attention 0 <= 2.8.3.post1

flash-attention 0816ef12f424c6ec94b057a72c275b14f6e6edb2

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-62239 - Proof of Concept

References

https://github.com/Dao-AILab/flash-attention/issues/2637
technical-descriptionexploit
https://github.com/Dao-AILab/flash-attention/pull/2702
issue-tracking
https://github.com/Dao-AILab/flash-attention/commit/0816e...
patch

CVSS V4

Score:
5.3
Severity:
MEDIUM
Confidentiality:
High
Integrity:
High
Availability:
None
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

YU SUN
.